Lol dude this is a Steam character that you re-decorated. And this cat wants to use your image as a Steam prof pic. You don't have the legal rights to deny him permission. He asked you out of artist courtesy. Don't be an ass; graciously allow your fan art to be permitted and you'll make more friends.
I'm not trying to be an "ass", If he really wants to use it he/she could go ahead. I just asked him politely not to because I created the picture to show off my Source Filmmaker OC. I in no way was trying to discourage him/her from my art.
Poor choice of words on my part. I mean this character alone. I would appreciate it if they did not use it for their Steam id. Any of my other characters are fine for someone to use, as long as they credit me.