Hey Hitame.
Right now, I'm inclined to think this is a pretty weak character application. You say you think we need more Slytherins but if you look at the character stats thread, Slytherins are our second largest house. That's what that thread is there for, so use it in future.
To be honest with you, it looks to me like you're a fan of this singer and decided to make a character based on him. That isn't a good way of making a character because what happens next week when you're going through a Beatles fix and decide George Harrison would be a really good Hogwarts Professor?
Nevertheless, these are the things that need to be fixed before I can accept your app:
1. Your character's seems very modelled on his play-by. They share the same name and hobbies. Is there a reason for this?
2. Your character is sixteen. It's illegal for him to have a tattoo.
3. Unknown means your character is part of a single parent family. He does not know his mother. This will doubtless change his history.
4. In Kellin's history and personality, there is a lot of information about his sister wanting to hang around him and being "clingy". I need you to delete it because she is also a canon and putting that information into your history is like godmodding her.
This also means you will have to change your dementor and veritaserum answers.