These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Acceptable Targets: Linda is overweight. Subverted when you realise Wendy will bully anyone who dares opposing her. Also subverted in that Bruce, who's described as being fatter than Linda, is easily accepted by his peers.
Designated Hero: Jill. We're supposed to cheer for her even when she's being a bratty bitch, and then we're supposed to see her as the poor little victim when karma comes back to bite her in the ass.
Unfortunate Implications / Double Standard: Linda is bullied for being slightly pudgier than the other girls, but Bruce Bonaventura is the fattest kid in class and is accepted as one of the gang. The rationale seems to be that Bruce laughs at himself easily while Linda is shy and passive, but still.
Jerkass Woobie: It is hard not to feel a little sorry for Jill at times, bratty as she is.
In fairness, Linda's experience doesn't stop her from taking a complete role-reversal with Jill, as Wendy's sidekick in tormenting her. The closing pages suggest that this didn't last, but there's a bit of apparent Hobbes Was Right about her behaviour.