I like ones with well-done mental instability. I'm not just talking depression and/or being emo and being just two dimensional. I mean real problems: schizophrenia, borderline, bipolar. If they're done properly.
And I like ones that go through a complete change and you can see it. There's a THF story and its sequel -
Obloquy and
What Patience Brings - and the changes that Bill goes through after Tom's death feel
so goddamn real and they're done so well. His entire personality is done flawlessly. Him dealing with it and moving on, it's all incredible, because it's not done as some authors will do, where the character goes through everything in a short, sweet 12-chapter piece. It's a long process and it's not just getting over a loved one and falling in love and moving on. It's painful and long and lonely and terrifying and just... I don't even know. Characters that go through big, long, drastic changes and feel
real and alive to me.
And I like vain ones.
When they're realistically selfis/vain/narcisstic and you just want to slap them. I personally know how these type of people are and getting to read them done right is wonderful.