He's 2 years old, never been outside before, used to be the sweetest cat that would stalk me around the house and always want attention. He depended on me a lot since he was abused as a kitten and so I took him as my own. He was always an indoor cat and would be scared of outside. However few days ago he got out from the window being open (the screen was able to be pushed out so that's how he got out) I heard the sound around 10-11pm and just thought he was getting into stuff and went back to bed. When I woke up the screen was popped off in the corner so I looked everywhere my cat could of hid and he was no where so I began to look outside which he would of been outside for 13 hours the most. I then tried to look at shelters online to see if anything came up for my cat and sure enough, Scraps had him so I tried to rush there and found him! He was scared, dirty, I was the only one he let touch him so that's how I knew and the scraps helpers knew he was mine. Everything seemed correct, he was missing at night and was turned in that day, the cat was 2 years old, it even had the same bent tip of the tail as my cat. SO I got him home but he's been different since, it's now day 2 and he's still highly aggressive towards me. I haven't been able to take off the collar thing scraps put on him that's like paper or something with the date he was found. He hisses any time he gets too close to me or I try to sit somewhat close to him without actually trying to touch him. I've given him a treat and got to the point that he would try to come up to my fingers to get a treat as well but then he just snaps back into that state that his eyes change and attacks me again.
I don't know if he'll ever be the same that he used to be, is there any chance that he'll be back to normal?