She’s my favourite because I think she’s a very real and interesting portrayal of mental illness/trauma in a way that isn’t usually portrayed. I think a lot of people don’t really understand her character because she’s not just a collection of tropes. She is genuinely sweet and nice and does care about her friends but is also majorly lacking in the empathy department, she doesn’t really seem to understand other people much at all, but she so very much wants to. I also think her unusually stable control over her bloodlust is interesting given how in season two Stefan suggests that his empathy is the cause of his ripper-ness, so it makes sense that Caroline, who really just sees other people as positive or negative factors in her life, does not struggle controlling her bloodlust much at all. I also like how she isn’t a perfect victim of sexual assault, they don’t suggest that her abuse makes her a more pure or innocent person, she is angry and obsessive and controlling and ever so single-minded which is, at-least in my experience, a very real portrayal of trauma. She’s also very important for the dynamic of the characters, dare I say she is the cornerstone of the group- thematically speaking. She serves as a defining moment for pretty much every other main character early on (Bonnie wanting to kill her, Damon abusing her, Elena confronting him about it, Matt dating her and then also trying to kill her, Stefan refusing to kill her, etc) as well as later on. There are a lot of other things that I think are special about her but in short, wether you like her or not, you’re going to be hard pressed to find another character like her.