Zir could have just been that one troll that would periodically troll her if he got too bored. Meaning when the other trolls weren't in the mood to put up with his shit and were ignoring him and no longer fun to poke at. Which probably happens often enough.

And it would be a thing of beauty if at some point or another she could have linked him to a disney villain song. He needs corruption from as many kids as possible to go disney. this is my main goal with his interactions with any of the kids. disney corruption.