Me and my "sister" grew up in a quiet little suburb, just big enough for it's own police station but not big enough that everybody didn't know everybody else.
Mom and dad could never have kids and adopted me and my sister very young, we considered each other siblings nonetheless and some may have said we had brother/sister complexes, but at that time it was less like attraction and more like "ride or die".
Everything started to change around when I turned seven, new people started coming into town, first it was a new school headmaster who transferred to our little police station, we didn't find out why until it was too late. He called himself uncle Jack, he was fat, ugly in a way that almost made people pity him, and amazing at worming his way into people's hearts. He disguised it well but the smart kids avoided him like the plague, something just wasn't right about him, we children could tell instinctively but the adults just ignored it.
in spite of our misgivings he was wealthy and outwardly kind, he made donations, attended events, made face time with the adults and generally spread his disgusting self into as many lives as he could. Our parents even invited him to our house for dinner a couple times trying to get us to see that he wasn't too bad, but that stopped after the second time waking them up due to our nightmares afterwards.
Fast forward about five years, nothing overtly bad yet, though over time more and more of his cronies had transferred into the school as staff.
First it was small things, never in eyesight of anybody who may know better, first it was little things, the school staff being more open about "accidentally" brushing against breasts or butts, finding reasons to use the permanent record system against people who called them out. Then one of the girls in our class got caught shoplifting from the school store, she never even got her parents called, just a "trade" the teacher forgot anything happened in exchange for a handjob, and it only escalated from there. Most of the staff were somewhat restrained, at least at the beginning, but jack was always willing to push it. But fortunately for most of the girls in town he pushed too far when he targeted my sister.