Okay, fairly new here, but reading through these threads I want to jump up and down shouting "MY PEOPLE! I HAVE FOUND MY TRIBE!"
Re: Barry/Felicity and Sara/Oliver
I think these relationships both serve the same purpose. They're 100% solid, die-for-you friendships with possible sexual chemistry, but both only function on a temporary basis. Barry and Felicity can't get too far into a relationship before they realize they're almost exactly the same person and their relationship shouldn't get past cuddling on the couch while watching Netflix.
Sara and Oliver are a different story. In my mind they have a very unique bond because they survived on the island together and went through similar processes to become killers in need of redemption. They're perfect fuck buddies, but their relationship isn't necessarily romantic because together their outlook is too bleak for romantic love to exist. They only work for so long before they recognize being together drags them both back down to their worst selves, but I would put Sara as the fourth person Damien Darkh would put in the gas chamber boxes because she's as close to Oliver as Felicity, Thea and Diggle, but in a very different way. And yes, Laurel should have been manning the tip line, because she had no business associating with Oliver at all after season 1; and I can only interpret her sticking around as some kind of self-punishment to feed her martyr complex.
Laurel Lance is a tragedy. BKG obviously never consulted a woman during development because a woman would have smacked them over the head for thinking the toxic ex thing could work as the series "epic love story." But I digress.
It makes perfect sense to me that Oliver would sleep with Sara in 2x13. Shit just got real in his relationship with Felicity because she's always played it close to the chest with her personal life. She knows all about him, but he doesn't know much about her, so sharing the story about her father leaving is a pivotal moment for them... and Oliver is terrified. He's terrified because as far as he knows he'll only hurt Felicity emotionally because he knows he's a dick, and in comparison Sara is safe because she's just as closed off emotionally as he is.
I'm pretty sure Diggle knew exactly what Oliver was doing-- hooking up with Sara was really all about being scared of his really real feelings for Felicity; an act of avoidance-- if he doesn't acknowledge that he's kinda in love with Felicity in the grown up way that he's never experienced before, then those feelings don't exist, right? Diggle likely felt it wasn't his place because he didn't know the two of them back in the day, but somewhere in Heaven Tommy was shaking his head ruefully, going "you really are a complete dumbass, aren't you Ollie?" Thea would have also called him on his shit had she known the situation.
Laurel would have just made the whole thing about her and how everyone betrays her.
I so desperately wanted to like Laurel. At best she was a poorly constructed character I never found believable because the writing was so terrible, at worst she was a completely selfish, narcissistic bitch with very few likable qualities. Deep analysis makes me feel even her better parts were tainted with self-absorption; she only worked as a non-profit attorney so she'd get a pat on the back for being so "selfless." I always hate myself for thinking so lowly of her, but I can't deny what I see in the text.
Oh, and my point: One of the things that pissed me off about the Baby Mama story was that it tainted Felicity's friendship with Barry. Central City was her safe place, where she could go to be comforted whenever Oliver was being an ass, but because Barry was complicit in the deceit her safe place wasn't available. Where did she go during that montage where Laurel's all happy, laughing with her dad and eating lunch, Diggle is holding Sara, and Oliver is making his video confession to William?
Thank you, sweet Jesus, for Curtis and Paul. I like to think they've both been the Gay Best Friend before, and know how to comfort the broken-hearted with Ice Cream and Dirty Dancing. Because they're so similar, Barry should have known how much the revelation would hurt Felicity, but he let his man crush on Oliver overpower his natural sympathy.