Ugh, god I've had mine stolen before. I've had kids around 13-15 on tumbler steal the artwork of my ocs and then proceed to make rp blogs for them. They even went as so far as to steal the entire background and story for them! On one hand, I'm flattered that people actually think my characters are good enough to steal, but on the other hand, I want to do unspeakible things to the little hellions.
I've also had kids on tumbler "kin" with my characters and then proceed to think that they were them? They even started an ask blog too. It was hella weird. I politely asked them via pm to please take down their blog, and they told me that and I quote, "You were stealing my identity, so yeah I clearly don't need to do shit. You on the other hand, should be apologizing to me. You stole a part of me, and I just got it back." After telling me that, they blocked me and some of my friends who weren't involved in the situation either.
I finally got so pissed about it, and with no other options, I contacted a old buddy of mine from 4chan (don't worry, he got off the site for good like me XD), and had him hack their tumbler account and kill the blog. He owed me a lot of favors and a bag of cheetos. Was it morally right to do that? Ehhhhhh nah not really, but I didn't have any other options. ;w;"