Okay so I think that Annie wouldn’t really like Katniss at all before they actually met, and probably a bit after that. I think she would have been jealous of her, and yes, I have legitimate reasons. First, Katniss got away with having her little mental breakdowns. Think of it like this, how often in the books do we see Katniss curled up screaming her head off in the books? Quite a lot. Annie? None, she just laughs a bit and covers her ears sometimes. She controls herself for the most part. I imagine she wasn’t much worse when she was younger. But Katniss? She got away with it simply because she was from district twelve, and was therefore more susceptible to showing the trauma, bu she was still seen as a fighting figure. Someone to look up to and envy. While Annie was perceived as mad because she was from a career district and had a bit of humanity. That drives me mad myself sometimes.
Second, Katniss never had to fight for a relationship. Her “star crossed love” was basically worshipped by all of panem, and no one assumed there was anything behind the scenes. Not to mention, she was seventeen when it was announced that she was pregnant, which I feel would have made Annie horrid with jealousy. Judging by how quickly she was pregnant after the marriage, I’d say it’s fair to believe they’d wanted a child for quite some time, but we’re never allowed it. You see how much she loves Finnick, and he her, and they take every moment they have together to flaunt it once they can. But before? They can’t, and Katniss can at such a young age, which I think would make her so upset that it’s crazy.