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.
Some see Rose's behavior as a result of her mother's passing and that she should be pitied, while others refuse to handwave her behavior and see her as a bratty Attention Whore that is unnecessarily rude to Lily.
Base Breaker: Ben and Rose as individuals and as a pairing. Ben tends to get heat for not having properly atoned for the way he treated Rose in season 1, whereas Rose is seen by some as whiny, rude, hypocritically and bratty.
Crack Pairing: Lily/James has become a sort of car crash crackship, if only because they're disturbingly similar.
Les Yay: There's already canon lesbianism, but name two female characters, any two female characters, and you can probably make a pretty good argument for it, especially if Lily or Arianna are involved.
There's also a ton via flashback between the Nereids, some of which is blatant and some of which is only in subtext.