For identifying, I reflexively thought, no one! I usually don't think of fictional characters as someone to identify with. However! As it happens, Sirius is the one exception. This is because we've both had Azkaban- type experiences. He lost a great number of years there. I lost four years while I was unable to move from a severe illness. I would note that I was having birthdays without feeling as though time was actually passing. I therefore think of myself as younger than I am. Also, Sirius had to deal with Dementors. I had to deal with doctors. Same thing! ;) I must object when JKR says, "Sirius never grew up," thanks to his experience. It's not really like that. Just because you can't experience anything in the outside world doesn't mean that you're not experiencing things on the inside.