Supergirl Season 3: Up, Up and Speculate Away!

[JapMo]

8 hours ago, VCRTracking said:

The big complaints over on the Flash board is that the show is too centered on Barry. Yes, he's the star but it seems that all the other characters(particularly the West family) solely revolve around Barry. With Supergirl it's the opposite. All the other characters are leading their own lives, Alex, J'onn, Jimmy, Winn and even when she's in a relationship, it's Mon-El's arc.

I don't think it started out centered on Barry.  They showed a lot of West family time in previous seasons.  But this season, it really was all about Barry, and maybe Caitlyn.  

[roctavia]

I didn't mind the Mon el arc (aside from I hate his name and the way it sounds when people say it) and I didn't think he took over the show, at least for me.. Kara was still front and center- her feelings, her struggle with not feeling she could have a normal life or a happy relationship etc. Could they have done it better- sure, I think it could have stretched out a little longer, though at one point they did say he's been there for 9 months... But still, it could have used more time, but then the daxamite story wouldn't have worked.

If Mon el is sticking around, I'd actually like a show to let them have a semi normal relationship- not angst or clones and frogs or amnesia BS. Let them have a relationship that works most of the time, with a few ups and downs- because that's how it works in real life (if their goal is for Kara/Mon el to be the final pairing) and he can be a part of the team without taking it over, and we can still have cute moments where Kara hits new relationship milestones or whatever you want to call it. It can be done, but too many shows are afraid to let a couple be mostly happy.

I would like the villain to be better than just someone who wants to take over the world/destroy the world. Cadmus could have almost been that, but it's sort of gone of the rails for me. I assume the teaser krypton baby thing is going to be next seasons big bad, but I'm hoping for more nuance than just smash, take, punch.

[Katydid]

Anyone know if they are going to start filming season 3 in the very near future? David posted on Twitter about his hiatus being over and something about going back to save the word, with tags related to Supergirl.  It seems like they just finished season 2, and I thought they typically didn't start filming again until late July/August. 

[Starfish35]

According to this, they start filming July 6.

[Katydid]

Wow that's so soon.

[Last Time Lord]

I hope Supergirl, Flash, and Arrow do a time jump between seasons. I just feel the way each of those series ended their seasons could benefit from one, and each one for reasons unique to each show.

[JapMo]

On 6/12/2017 at 10:40 PM, roctavia said:

If Mon el is sticking around, I'd actually like a show to let them have a semi normal relationship- not angst or clones and frogs or amnesia BS. Let them have a relationship that works most of the time, with a few ups and downs- because that's how it works in real life (if their goal is for Kara/Mon el to be the final pairing) and he can be a part of the team without taking it over, and we can still have cute moments where Kara hits new relationship milestones or whatever you want to call it. It can be done, but too many shows are afraid to let a couple be mostly happy.

I don't understand why shows are so reluctant to do this.  If you are a writer, that would be a challenge to come up with ideas to keep the coupling fresh.  Not challenging....just a challenge to try to buck the trend and not use stupid misunderstandings and phony kidnappings to keep the couple apart.  The key is to have their own life too...and at least Mon-El has a job at a bar where he does something other than prop Kara up.  Over on The Flash, they've had a problem for years trying to give Iris something to do.  She has nothing...no outside life other than Star Labs.  She's with Barry 24-7, living AND working with him.

[roctavia]

6 hours ago, JapMo said:

I don't understand why shows are so reluctant to do this.  If you are a writer, that would be a challenge to come up with ideas to keep the coupling fresh.  Not challenging....just a challenge to try to buck the trend and not use stupid misunderstandings and phony kidnappings to keep the couple apart.  The key is to have their own life too...and at least Mon-El has a job at a bar where he does something other than prop Kara up.  Over on The Flash, they've had a problem for years trying to give Iris something to do.  She has nothing...no outside life other than Star Labs.  She's with Barry 24-7, living AND working with him.

I guess they fear the moonlighting curse??  But it can be done... there are shows that start off with a couple already together that stay together, though I do suppose these tend to be more comedies vs dramas, but it could be done on a superhero show or anything else... It just has to be done well to keep some of the sexual tension there, a little mystery, some conflicts that aren't earth shattering and relationship ending... Life is full of problems that can be worked out if they need some extra drama... but yes, have characters together and let them still have separate storylines/lives. Happy couples are not always boring, showrunners!!

[Cranberry]

Agreed. Look at Friday Night Lights, or even Castle (once they moved past the Moonlighting-type stuff). Or Elementary. Sherlock and Joan Watson have a (wonderfully) platonic relationship, but a deep and supportive one, and their conflicts are organic. Or, on a comedy, Brooklyn Nine-Nine's Jake and Amy, who don't overpower the show and who don't engage in dumb drama.

[The Crazed Spruce]

Just a reminder, speculation threads are meant to be spoiler free.  So if you have any actual info about the new season, save it for the spoiler thread.

[Jacks-Son]

On 6/12/2017 at 11:40 PM, roctavia said:

If Mon el is sticking around, I'd actually like a show to let them have a semi normal relationship- not angst or clones and frogs or amnesia BS. Let them have a relationship that works most of the time, with a few ups and downs- because that's how it works in real life (if their goal is for Kara/Mon el to be the final pairing) and he can be a part of the team without taking it over, and we can still have cute moments where Kara hits new relationship milestones or whatever you want to call it. It can be done, but too many shows are afraid to let a couple be mostly happy.

LOL, sorry, I just got around to reading this. I gather you're talking about, "Lois and Clark, The New Adventures of Superman". Yeah, that couple could never be happy until the very end, and even the last episode with the baby left on the doorstep was kid of weak. Fake weddings, Lois' amnesia, marrying clones who eat frogs, that was some weird sh*t they put out towards the end. Hopefully, "Supergirl" will never stoop to ridiculous plot lines, although James' Guardian story line is cutting it close.

[JapMo]

On ‎7‎/‎27‎/‎2017 at 2:19 AM, Jacks-Son said:

LOL, sorry, I just got around to reading this. I gather you're talking about, "Lois and Clark, The New Adventures of Superman". Yeah, that couple could never be happy until the very end, and even the last episode with the baby left on the doorstep was kid of weak. Fake weddings, Lois' amnesia, marrying clones who eat frogs, that was some weird sh*t they put out towards the end. Hopefully, "Supergirl" will never stoop to ridiculous plot lines, although James' Guardian story line is cutting it close.

Just saw this.  Yeah, I remember week after week waiting for that wedding, only to basically have it ruined because the show was apparently so worried that once they got married it would be all over, so instead they ruined it anyway before the big event with some of the stupidest plots ever.  I have discussed TV shows with many people, and whenever the subject of Lois & Clark comes up, that's the second thing people talk about.  First they say how much they LOVED the show, and then they say how awful it was near the end when the writers kept L&C from getting married for like 6 episodes with ridiculous plot lines.

[Wiendish Fitch]

My Top 10 hopes for Season 3:

1. More Cat Grant. I never, ever thought I'd say this, but I've missed you, Calista Flockhart!

2. Less Guardian. In fact, no more Guardian, that storyline was beyond stupid.

3. I want to see more of Kara developing her reporting skills. I loved seeing her win Snapper Carr's respect. 

4. Hire writers who know how to write relationships, because all of the relationships on this show are friggin' weak. No one has chemistry, couples break up and get back together every other episode, no one knows how to behave like a rational human being (or even alien), it's just getting embarrassing. 

5. Maybe this is a UO, but I happen to really like Kara and Lena's friendship, and I wouldn't mind seeing more of it. I don't know if Lena's going to turn evil (she is a Luthor, after all), but I wouldn't be surprised if it happens, so I wouldn't mind seeing the one decent relationship on this show play out a little longer.

6. Can't they find some way to write Winn out of the show? I'm sick of his whiny ass.

7. I've read rumors from last year of Power Girl appearing on The Flash. Who knows if they'll do it, but how about having her appear on Supergirl instead? It would make way more sense, I would love to see Power Girl fight alongside Supergirl, and the contrast between their personalities (Power Girl's spice to Supergirl's sugar).

8. Can they please find a better actor to play Superman?! Tyler Hoechlin is just awful; he has the wrong look, wrong physique (his Superman is rather twerpy), and he always looks confused.

9. End the Jeremiah Danvers storyline. Enough is enough, it needs to run its course.

10. More appearances of DC heroes and villains, because I don't care how gimmicky they are, I love 'em. Heck, I would love a cameo by C-list characters like Booster Gold, because no one would ever see it coming. 

[legaleagle53]

2 hours ago, Wiendish Fitch said:

8. Can they please find a better actor to play Superman?! Tyler Hoechlin is just awful; he has the wrong look, wrong physique (his Superman is rather twerpy), and he always looks confused.

Brandon Routh was already taken.  He's playing Ray Palmer/The Atom on Legends of Tomorrow -- and if you think Tyler Hoechlin's Superman looks confused and twerpy, you should see how big a dork Ray is!

Edited August 22, 2017 by legaleagle53

[The Crazed Spruce]

On 8/21/2017 at 10:15 PM, Wiendish Fitch said:

7. I've read rumors from last year of Power Girl appearing on The Flash. Who knows if they'll do it, but how about having her appear on Supergirl instead? It would make way more sense, I would love to see Power Girl fight alongside Supergirl, and the contrast between their personalities (Power Girl's spice to Supergirl's sugar).

Well, since Power Girl in the comics was originally the Earth-2 version of Supergirl, I think she'd work a lot better in The Flash, storywise. I'd love to see 'em cross the two characters over, though.

[tinnefoil]

1.) How do think the Reign arc will end? I see a lot of people speculating that Kara will die and be reborn because of how they've been hyping Reign up as the ultimate enemy, kind of like Doomsday for Superman. I think with the way they are heavily suggesting that Alex might get to parent Ruby, I think the chances are very high that Reign will die. So if she dies, will it be Kara who kills her and struggles with the guilt that by killing Reign she also kills Sam who doesn't deserve it? Or will it be like Alex/Astra where somebody else ends up killing Reign?

2.) Who do you think will be first to figure out that Sam=Reign? 

3.) Will they ever explain what was up with the dream Kara and Sam had in the first episode where it looked like they were sharing a dream and Sam was seeing Alura? 

[johnar]

On 5/23/2017 at 0:22 AM, Kromm said:

Speculation, but targeted specifically for Season 3. I recall that some show forums do this and then merge it back into the general spec topic when the season starts. So I hope this is okay in this forum, given that frequent precedent.

I'll go first.

Mon-El's portal trip takes him to the 31st Century. He comes back early in Season 3 very different. A lot more mature, with a costume, and lots of secrets. Foremost among them that he knows the future and can't talk about it.

Yes, he's been away with The Legion of Superheroes. Whether or not any of that is shown on-screen via Flashback, via some important cross-over episode later in the season, or not at all, is not something I've thought all the way through. They could do it any of those ways.

Pretty good speculation!

[johnar]

On 1/13/2018 at 4:00 AM, tinnefoil said:

1.) How do think the Reign arc will end? I see a lot of people speculating that Kara will die and be reborn because of how they've been hyping Reign up as the ultimate enemy, kind of like Doomsday for Superman. I think with the way they are heavily suggesting that Alex might get to parent Ruby, I think the chances are very high that Reign will die. So if she dies, will it be Kara who kills her and struggles with the guilt that by killing Reign she also kills Sam who doesn't deserve it? Or will it be like Alex/Astra where somebody else ends up killing Reign?

2.) Who do you think will be first to figure out that Sam=Reign? 

3.) Will they ever explain what was up with the dream Kara and Sam had in the first episode where it looked like they were sharing a dream and Sam was seeing Alura? 

I believe James Olsen will die (and Mehcad Brooks will leave the show). His Guardian character did not go over well at all. I may be wrong about this, but judging by the way his hero alias bombed, the general back burner position of his role on Supergirl, the unlikely pairing of him and Lena (usually a sign one of the two is about to die off leaving behind a grieving lover) ← Winn's character would have qualified as a possible candidate for this if his 2nd season girlfriend was in the 3rd season at all. But what sold me on this hunch was seeing the Guardian killed off on Earth X. 

Also I believe the team (Alex, Hank, Winn, James, Lena) will figure out Reign gains her power from darkness the way the Supers do from yellow sunlight. This was more or less why Supergirl got her ass handed to her for real (as opposed to merely getting the wind knocked out of her last season). Reign fighting at night is continuously charged. Kara and Clark are running on battery power until the next day.  ←If not, #supergirlprod & #supergirlstaff missed out on yet another brilliant idea (I have tried relentlessly to get them to listen to my ideas).

To answer (at long last ha ha) question number 1:

I think Reign will be tag teamed by a revived Kara and a really ticked off Clark using some device whipped up by Winn to bring sunlight into night... perhaps a network of reflective satellites. Some have speculated the Legion of Mon-El and Saturn Girl plus whoever is revived in the sleeper ship will kick Reign's tush. ← This would not surprise me as it sure seems like Supergirl showrunners are trying to write out the original cast of the show as quickly as possible... they have been on the sidelines for over a year now. 

2: Her daughter Ruby. And especially when she finds out what happened to Supergirl (the winter finale seemed to indicate she does not know yet that Supergirl was nearly killed) she will go to Alex with the truth.

3. Not sure I recall what you are talking about. Must have just been a flash or my memory is slipping.

[johnar]

Just now, johnar said:

I believe James Olsen will die (and Mehcad Brooks will leave the show). His Guardian character did not go over well at all. I may be wrong about this, but judging by the way his hero alias bombed, the general back burner position of his role on Supergirl, the unlikely pairing of him and Lena (usually a sign one of the two is about to die off leaving behind a grieving lover) ← Winn's character would have qualified as a possible candidate for this if his 2nd season girlfriend was in the 3rd season at all. But what sold me on this hunch was seeing the Guardian killed off on Earth X. 

Also I believe the team (Alex, Hank, Winn, James, Lena) will figure out Reign gains her power from darkness the way the Supers do from yellow sunlight. This was more or less why Supergirl got her ass handed to her for real (as opposed to merely getting the wind knocked out of her last season). Reign fighting at night is continuously charged. Kara and Clark are running on battery power until the next day.  ←If not, #supergirlprod & #supergirlstaff missed out on yet another brilliant idea (I have tried relentlessly to get them to listen to my ideas).

Before season 2 began I pitched the hero idea to Supergirl showrunners for James Olsen.

I wrote a passionate break up scene with he and Kara with James doing the breaking up (which would have gained Kara sympathy from the audience). The sloppy way it was done in the season 2 opener made Kara seem like a flake. "Oo oo, I want me some of dat" one day, then suddenly, "Pass..." OR (even worse) it made Kara out to be interested in James as long as there was another woman in his life. "Oo oo, I want what SHE'S got!" Both are bad female stereotypes.

Our hero. {sigh}

Sometimes I seriously wonder if CBS President Leslie Moonves is the only one who truly wanted Supergirl to survive after season 1. 

But if James had broken up with Kara she would have the drama rights to several episodes. "Boo hoo James won't have me." and the fans would go "Awww, our sweet sweet Kara got dumped." 

Now you'd think the audience would be major P.O.ed at James... but this was the beauty of the way I wrote it... (tooting own horn, yeah yeah) James would have done so #1 before it really got started in the first place... and #2 because of what Lucy tried to tell him about the supers and their relationship being continually interrupted. Then James would say "I saw for years myself, Lucy's sister Lois living in the shadow of Clark. And what it did to her. I just can't be that for you. I'm sorry. The superhero doesn't always get the guy..."

At this point Kara goes from brokenhearted to furiously angry. "That's exactly what Winn said!" A year earlier Winn said precisely this to Kara about she and James. "He's been poisoning you against 'us.'" She's mad enough to rip Winn's head off. 

"Now just a minute," James said. "Hold on. Winn would never do such a thing."

Kara is livid, "Oh really? He said what you just said about 'the superhero' when I was, uh, in, pursuit of you." A bit more timid now.

James replies, "Kara, Winn urged me to pursue you when I was on the fence."

"What?" she says surprised.

"Yep. He did. Even though it broke his heart. Because he knew it would make you... happy."

She is flabbergasted. "I don't believe it.

"Believe it, Kara." James is quite frank. "That's true love. Putting your feeling above his own. And. I'm just not a man like that for you."

(I write better in script / screenplay format where you assign a name to the dialogue... novel writing has never been my forte).

Then I had a scene where Lois comes to congratulate James on his promotion then sucker punches him for breaking her little sister's heart. Then she demands he call Lucy (because she's constantly calling Lois and crying and driving her nuts). "Fix it!"

He does and Lucy takes him back on the provision he never have anything to do with a Super again. No matter what. Even if it were to save her life. James promises and they begin a new life together. An as you would expect Lucy is killed by something a Super could have prevented.  In fact, Supergirl arrives on the scene but too late to save her.

"Why?! James, why didn't you call me? I could have saved her. "

James, over her lifeless body, sobs. And he manages to utter, "I was keeping my word."

After a time of aimless wandering, James finds himself in several situations where he is helping people below the radar... out of the press and media... and in time it seems to be a purpose even a calling. He contacts Hank Henshaw to be trained and to acquire several alien devices in DEO storage (a blaster, a hover cycle, and interface shades [like DC Comics' answer to the Jarvis uplink in Ironman]) to become the underground vigilante the Lone Wolf. I even saw it as a spin-off series and if they had bought it in 2016 it would have been the first superhero TV show with an African American in the title role.

 

Too bad.

[johnar]

No spoilers go to thread that allows spoilers...

tee hee

Edited January 15, 2018 by johnar

[tinnefoil]

Well, I hope they don't bring Clark for the finale again, imo that would undermine Supergirl too much as the main hero. They should bring him on during the season, establish that he isn't effective against Reign either and leave it at that. I don't think that the Legion will be that effective, it would be too early in the season, Reign is definitely not going down before the finale. 

Winn had nothing to do all season but in favor of Lena and Sam, Mon-El and the Legion weren't even on screen at that point. And it's not like Superman is original cast either. And the Legion is a big part of Supergirl's history in the comics and as a comic fan it would make me very happy if we got some of the core moments, like Supergirl receiving a Legion ring and Supergirl/Brainiac 5 being referenced. And getting to see a big flying charge led by Supergirl would be awesome to see.

Quote

3. Not sure I recall what you are talking about. Must have just been a flash or my memory is slipping.

It was in the very first episode of the season. Kara had these sweeping dreams of walking in a yellow field and seeing Mon-El dressed in white and Alura dressed in blue. The episode ended with Sam having a dream of Alura turning to her and turning into a monster with spikey teeth. Some people think that this is Reign's true form will be like. I think it speaks to the show's poor handling if people have forgotten about this already, I remember a lot of reviews back then thinking that that was a major twist, that Sam might be connected to Alura in some way.

It makes me wonder whether they'll ever bother to adress that. There was this really small moment in episode 5 where Kara and Sam talked and mentioned that both of them had trouble sleeping which I thought was a reference to this, but it hasn't really come up since. 

I could picture Ruby being the first to find out, but I don't think that just seeing the Reign and Supergirl fight would be enough to tip her off, with Reign having a mask and a disguised voice. 

Well, I for one hope they don't kill James. They haven't really stressed his friendship with Kara much this season, and him just being killed off so Lena can cry would bother me a lot and I think most people would find it pretty dumb if her lover dying was a major factor in turning Lena closer to darkness. 

Edited January 15, 2018 by tinnefoil

[johnar]

58 minutes ago, tinnefoil said:

Well, I hope they don't bring Clark for the finale again, imo that would undermine Supergirl too much as the main hero. They should bring him on during the season, establish that he isn't effective against Reign either and leave it at that. I don't think that the Legion will be that effective, it would be too early in the season, Reign is definitely not going down before the finale. 

Winn had nothing to do all season but in favor of Lena and Sam, Mon-El and the Legion weren't even on screen at that point. And it's not like Superman is original cast either. And the Legion is a big part of Supergirl's history in the comics and as a comic fan it would make me very happy if we got some of the core moments, like Supergirl receiving a Legion ring and Supergirl/Brainiac 5 being referenced. And getting to see a big flying charge led by Supergirl would be awesome to see.

It was in the very first episode of the season. Kara had these sweeping dreams of walking in a yellow field and seeing Mon-El dressed in white and Alura dressed in blue. The episode ended with Sam having a dream of Alura turning to her and turning into a monster with spikey teeth. Some people think that this is Reign's true form will be like. I think it speaks to the show's poor handling if people have forgotten about this already, I remember a lot of reviews back then thinking that that was a major twist, that Sam might be connected to Alura in some way.

It makes me wonder whether they'll ever bother to adress that. There was this really small moment in episode 5 where Kara and Sam talked and mentioned that both of them had trouble sleeping which I thought was a reference to this, but it hasn't really come up since. 

I could picture Ruby being the first to find out, but I don't think that just seeing the Reign and Supergirl fight would be enough to tip her off, with Reign having a mask and a disguised voice. 

Well, I for one hope they don't kill James. They haven't really stressed his friendship with Kara much this season, and him just being killed off so Lena can cry would bother me a lot and I think most people would find it pretty dumb if her lover dying was a major factor in turning Lena closer to darkness. 

Me too. But just a hunch. Mehcad was one of the three in the cast who was really all in with the franchise move to Vancouver. For a few months now, not so much. His twitter site had Vancouver as his home. For a couple months now it has been back to Austin, Texas.  Same way with Jeremy Jordan. Was Vancouver on his twitter site now NYC.

But what cinched it for me that it was James was the death scene in Earth X.

Thanks for the reminder. It doesn't make sense to me unless Alura had a dark side / second life. But that's just me, I s'pose.

Maybe the girls only club the show is turning into will work for some. But Supergirl was a hero for all and everyone could cheer her on. Guys felt like we could even appreciate the sister scenes. But increasingly we are feeling locked out. As I said, if that the direction they want to go in and they can survive yet another block loss of fans, then go girl!

But it will never be what it could have been in the season 1 format.

Edited January 15, 2018 by johnar

[bettername2come]

On 1/13/2018 at 5:00 AM, tinnefoil said:

1.) How do think the Reign arc will end? I see a lot of people speculating that Kara will die and be reborn because of how they've been hyping Reign up as the ultimate enemy, kind of like Doomsday for Superman. I think with the way they are heavily suggesting that Alex might get to parent Ruby, I think the chances are very high that Reign will die. So if she dies, will it be Kara who kills her and struggles with the guilt that by killing Reign she also kills Sam who doesn't deserve it? Or will it be like Alex/Astra where somebody else ends up killing Reign?

2.) Who do you think will be first to figure out that Sam=Reign? 

1. I'm convinced that Reign will die leading Alex to adopt Ruby, who will begin having powers since she's half Kryptonian. Alex does have experience with Kryptonian teenage girls, and they've pushed that mom angle hard with her. I kind of think Sam will sacrifice herself to stop Reign/save Ruby.

2. If it's not Alex after her clues tonight, I will be deeply disappointed in her.

[Trini]

When I first read about Reign/Sam and her not knowing she was a worldkiller, I thought it would be a story about Sam struggling to accept or reject her 'destiny'. I thought that if she went full villain then she'd have to die, and if not, she could still be redeemed and/or fight on the heroes' side. However, since they decided to go with the 'light switch'/split personality route, one way I can see them getting a happy ending out of this (even with Reign as a villain) is by them somehow erasing or the Reign personality, leaving Sam intact - probably with no powers. I mean, if they can switch 'on' Reign, then they should be able to switch her 'off'.

And yeah, I know that sounds ridiculous and simplistic, but that's how they set up this story from the start.

[tinnefoil]

My money is still on Sam dying a hero by killing/sacrificing herself and Reign in the process. Just like Livewire died as a hero. 

Kind of like, nobody can defeat Reign, only Reign (Sam) can defeat herself. 

[ahisma]

Alright, my guess for Imra's big secret: This whole trip back in time and present-day wakeup was to deliver Mon-El back to his original timeline. Probably something along the lines of, they told him that Earth lost a whole bunch of historical records, but they did have some that showed all of them fighting as a team in our timeline, and there were records of Kara and Mon-El doing things together past today's date, so they knew he had to come back. They have all the info to save the future in their DNA, so they'll fix the ship and continue on to their proper timeline, and leave Mon-El.

[lion10]

Here's my theory: 

In 3x10, Imra said that in the 25th Century, there's an unknown cataclysm that wipes out Earth's population and its culture, leaving a massive gap in history.  Mon-El says in the same episode that all that's known in regards to Supergirl and Reign in the 21st century is that Supergirl recovers from her injuries and that "Reign leaves".  And now Imra's saying that she needs to tell him the real reason they came to the 21st century.

My theory is that the Legion has traveled back in time to change the timeline from their current one and to help Supergirl either kill or defeat the Worldkillers; I'm leaning towards "kill".  In the original timeline, Supergirl has her initial fight with Reign and it ends the same way that we saw in 3x09 with Kara badly beaten, but the DEO's able to heal her and Alex helps Kara out of her coma with the same tech that Alex used to get Kara out of her Black Mercy fantasy.  At some later point, Kara and the DEO fight Reign, Purity, and Pestilence and this battle results in Kara's death and the heavy wounding of Reign, with possibly Purity and Pestilence being killed. The Worldkillers leave Earth to recover and take centuries to do so until they return in the 25th century to "cleanse" Earth, resulting in the cataclysm that Imra talked about in 3x10.

There's several clues that support this, but I'm doing a fair amount of guesswork.  First off, Reign's fate is left so ambiguous that it begs a more defined reveal at some point in the season.  "Reign leaves", meaning that she isn't dead but also because the destruction of Earth doesn't occur until 2455 means that she didn't finish her job, and we know that she's got a very singular focus.  Her job is to cleanse the world of sin, but she's an extremist with a "if you're not for me you're against me" viewpoint, so perhaps Reign's mission evolves into wiping out life on Earth to start fresh.  And after seeing Purity in last night's episode, I feel like she might be responsible for wiping out the Earth's culture; it could just be a byproduct of the apocalypse, but it fits with Purity's name to purge the world, especially depending on how broad her definition of "sin" is.  I also think that whatever Imra saw when Psi accidentally blasted her is related to Reign and that her vision will serve to drive the plot later in the season.

So why not tell Kara or Mon-El from the beginning?  The Legion knows based on what Mon-El's told them that Kara is strongly against killing, especially if she were to find out that Sam was unwillingly Reign.  And if they told Mon-El, he'd tell Kara.  Now if this theory is true, what does that mean for the Legion's timeline?  Idk.