Ivy's Links
Holly and Ivy are never assumed to be twins due to their contrasting looks and personalities. Holly often finds Ivy annoying, just wanting to preserve animals in peace without her sister whining that they're scarying away boys or too gross to make acceptable bedroom decorations. Their interest in science is one of the few hobbies they share in common, and Holly can appreciate her sister's intelligence and input on situations. For the most part, Holly gets on well with her twin and even indulges in their 'twinspeak' language and will often take Ivy's side (although this is because Holly sees it as the least taxing option).
Ivy and Judy are too similair to get along, always arguing and winding each other up. Judy wants to be prettier and smarter than Ivy, seeing her as her competition and wanting to 'beat' her. While this persists as a child, Judy begins to get on Ivy a lot better as she grows older and wants Ivy to teach her about make up and clothes and boys. She has a habit of 'borrowing' Ivy's clothes and wanting to go wherever her older sister is going, eventually viewing Ivy as very cool.