Jace: you're a werewolf. Sometimes, when your feelings take over you can lash out but you always know for sure that Jace will be there to stop you.
Alec: you're a shadowhunter, though you have the ability to cast magic. Your family came from a long breed of Seelies who were forced to turn into shadowhunters. You can cast spells only to be used by Seelies but you can also wear runes.
Magnus: you're a vampire, though because Jace owed Magnus something, he gave his blood to you so you could become a daylighter.
Simon: you're a warlock, who has been living for a long while. When he first met you, he asked "have you been fan for long?" Pointing at your fan shirt. You teased him with "since decades."
Raphael: a werewolf. Though you were almost turned into an vampire. But he saved you, because he didn't want you to become as him.
Sebastian: you're a shadow hunter, not actually from New York, but you moved here to be with your friends and to train and be a better fighter. You're amazing with fighting, and even beats him once every while.