(Let me return the favor)
Which character simply loathes your character’s presence?
The most obvious choice for this position would be Merula, but I don't think she actually hated Rosy (or MC in general). In first years it looked more like she was trying to raise her own reputation by defeating someone well-known and intimidating, and with all the fuss the Daily prophet raised around Rosy, she was a perfect target. It became more intense with time since Rosy reciprocated all her attempts of bullying (smashed her face to table in potions at least once), but Merula also had some shit going on in her personal life, so her standards of hatred were rather difficult to reach.
The one who actually did loathe Rosy with his entire heart and soul was Professor Snape. I imagine that Jakub and Duncan were in sixth year when he started teaching, and they had absolutely no respect for him as a professor or a human being. So, Snape did his thing, and blamed Rosy for everything her brother had done. What he didn't take in account is that she was a very high resistance little shit, and every time he punished her for something she didn't do it only motivated her to do something worthy of punishment. Also, let's not forget that he hates loud and troublesome children, and Rosy is a definition of those characteristics. And she smashed his student's face in a table.
