I just finished re-reading Ballads tonight and I have to say, reading it through this time I felt a lot less sorry for Snow than I did the first time. Yes, he was absolutely a victim of his circumstances (starting with the war which took both of his parents from him, and then a decade of being on the brink of starvation and overall despair of life) but there was a coldness, an absolute lack of compassion for anyone who wasn't able to help him advance himself in some way, which was present the entire story. This wasn't something that grew in him as time went on, it was always there. I think I was trying to give him the benefit of the doubt because of Tigris' obvious affection for him, and she is a genuinely good person, but I think she was blinded by her familial love for him to see him for the monster he really was. He is truly a horrible, horrible person.
I had managed to forget that Sejanus was hanged at the end, but once it became clear that's where it was going my heart just sank. I literally felt sick to my stomach. Still do. It's bedtime but I'm going to have to wait a while or my dreams will be horrid. 😞
Now, to the theory I've been teasing -- I believe after Snow went back to the Capitol, he worked with the Nazi-like doctors in the lab and had them modify the mockingjays to spy on the Districts the way the jabberjays were designed to do. The Districts had already gotten used to the presence of the mockingjays and felt that they were a private joke, a reminder of how they had gotten one up on the Capitol, but Snow knew that too. Lucy Gray told him the story. I believe he turned around and used the mockingjays against them as his own private joke of sorts - and worse, I believe the birds were modified to identify DNA markers (the way the rainbow snakes were) and report back when they had recorded specific people and/or their offspring. Starting off he probably wanted to confirm to himself that Lucy Gray was dead (if no bird ever came back with her recorded voice, it would confirm she wasn't out there anywhere) but then it branched out to spying on the Covey and from there, anyone who might become a problem for the Capitol. The movie confirms that the District citizens had their DNA markers on file (they had to have a finger prick when lining up for the reapings to verify that they were present) and when the jabberjays attack in Catching Fire, they had the specific voices of everyone that the victims knew and loved. The book even mentions Gale's little sister Posey, who the Gamemakers would have no reason to interview so they wouldn't have gotten her voice that way. I believe the Districts were being spied on for decades and didn't even know it, because they would never notice mockingjays flying around or think anything of it. The mockingjays fell silent when they heard certain people singing, Katniss mentions this more than once in the trilogy. And the jabberjays were designed to be silent while they were recording. Snow even noticed that the mockingjays fell silent when Lucy Gray was singing, that might have even given him the idea. Lord, he makes me sick to my stomach.
I might have more thoughts tomorrow but for now, that's enough.