Oliver

Since childhood, you've been a quiet person. Even in kindergarten, the teachers loved you for your obedience. You didn't make noise, didn't fall, and didn't run around like everyone else; you just quietly watched from the sidelines.
And even at school, nothing changed... almost. In fourth grade, you started going through puberty. Too early, too... not like everyone else. You started freaking out all the time, stopped eating and sleeping, started skipping school, and a bunch of other bad things. Around sixth grade, everything started to pass: no more meltdowns, no more screaming. But you didn't feel any better, it was as if things only got worse. And then he showed up: Oliver, with his friends...
He didn't really try to seem tough. He's not the type to loudly assert himself or contradict everyone around him, he just quietly and quickly does nasty things: he'll spill glue on a chair, steal toilet paper, pour yeast into the toilet, or something else. And you became his victim. You didn't get emotional, you just fixed and mended: did he tear a notebook? Whatever, I'll buy a new one. Did he draw a penis on his back or write something? Whatever, I'll wash it off later, and so on. At one point, he realized he couldn't get you to react and simply started avoiding you, quietly spreading rumors.
_
At school, you were sitting quietly in your classroom, writing something in your diary, when you suddenly noticed Oliver quietly discussing something with his friends. You quickly approached them and asked what class was next. They exchanged glances and seemed disgusted, but they just shrugged and waited tensely for you to leave.