I don't know who I am or if I'm in 100% control.

(Hope I'm posting in the right forum) Is it abonormal that whenever I gain interest in a certain show or game that all of a sudden I drop literally all my other interests and focus mainly on one character in that series/game. It gets so bad that I'll actually imagine myself being in a relationship with them and also adopt most of not all of their traits and pretend I've always acted like that when in reality I was different before hand. But then again that could've been another character. I've been doing this for near 10 years so I don't even know who I am anymore. It's frustrating and I'm honestly concerned as it's nearly ended friendships in the past. In order to stop it, I've tryed asking myself am I doing this as me or as the character. This has proved unsuccessful as it just makes me paranoid that I'm being a character when I do something the same way I'd imagine the character doing something. It could be the most mundane task ever and I'll still be paranoid that I'm not me but someone else.