I think if you've put a lot of effort into a character, through writing, drawing, gif making, appropriating them, it's inevitable that you will sometimes get jealousy and possession rearing its head. I do think most humans have these feelings, the "back off that's mine" is useful in certain contexts. So is getting angry at disrespect and getting sad. Getting possessive at what is "yours" is normal, it shows up in toddlers and they too need to learn how to behave.
In fandom, what is yours is the reflexion you have constructed, that lives inside of you, not a shard of actual reality. If you subscribe to "death of the author" theories, even they don't own the characters they made. The character is a concept, a construct, and you're host to a shard.
So, I know (and experience) that the feeling of interpretations you don't like is not always pleasant. I still think one of the better ways to not go off the fandom rails is to interact often and repeatedly with other views of your pet character. Sort of like your personality, a character is a receptacle for concepts, and it can contain multitudes. I'm not saying you have to like the interpretation of others. I'm not saying that if things are stressful because you are going through a Rough Time, you can't curate your timeline. You're a big person, you know when you're too fragile for friction or not. But when you aren't, I do believe that confrontation with other views - even those you dislike - is a net good.
As a sidenote: examine what you dislike. It can be just your sense of ownership that tingles. But it could be that you don't like seeing this trait emphasized, or that side of her/him. Ask yourself why you like / dislike things, what it reminds you of. Those uncomfortable moments are pockets for growth.
