I can't give away the plot so I can't say who the character is really but I read "My Sweet Girl" by Amanda Jayatissa when I was trying to read books by asian authors (the authors sri lankan) I really disliked the main adult character once I found out her secret and who she was, when before I found out I was like what could she have done so horrible when she was 12,
the flashback parts of the story, told from the POV of a 12 year old girl in a sri lankan orphanage, I really liked and liked that character's child version and was like "I love children" and disgusted by the villains/adults then
oh so then I'll add
the pedophile who was in his 20s but attracted to this 12 year old girl and she was supposed to be happy she got attention, then sexually assualted her in exchange for unrestraining her, the adults who drugged, physically restrained with straitjackets and the like, confined in small cupboards, and lied about injuries of children who were attacked (not gonna say by who bc that would be a spoiler), and made them seem crazy as well as making children who witnessed smth (can’t say what bc spoiler) seem crazy and like they were imagining this all to keep up appearances to keep funding when NONE of this would’ve happened if one person hasn’t done smth illegal and also depriving someone of needed help to keep up personal (not orphanage appearances
Since I mentioned this after Oliver twistI think there's a pattern here (minus the main character one)
all children deserve love not all get it
Edit: ok then since you mentioned a Harry Potter character I’ll add Harry’s aunt and uncle For locking him in a cupboard stealing his letters and presents locking him in his room with prison bars on his window giving him worse food and presents than Dudley treating him like a servant bc that’s child abuse too