[@Squirrel98] No worries I try not to play minors in role plays either way so that works out fine. Well way I figure it he can be maybe about 23, that's a good round age and the difference isn't creepily unrealistic. The age would determine how long he has been there for, I was thinking at least over five years or more with no chance of ever getting out. As for the reasons for him being there, could leave that as a surprise but add in some hints here and there in his bio to keep the ball rolling. 

I can picture a very quiet person, doesn't talk to no one (beside Cissy) everyone is weary of him due to past incidents so everyone kind of gives him a wide birth. A character haunted by a mysterious past that drives him to find companionship in an eighteen year old girl.  A secret violent nature perhaps, maybe even contributed to obsessive tendencies. On the outside he is almost emotionless, as if he doesn't even care about anything at all, extremely cold and decisive when he needs to be. But on the inside chaotic and unstable. This is one general idea anyways, I can probably think much more in depth after I catch some sleep been up 24 hours again.