So first, lemme explain relationships

Twilight married Flash and had Starswirl, unfortunatelly they did not work together, both helped each other realize that wasn’t what they wanted. They divorce, Flash marries Sunburst and Twilight stays a single mom (They’re still really good friends tho). Flash and Sunburst have a daughter (with the help of Starlight Glimmer, as a surrogate mother kinda). That leaves Starswirl and Moonshine as half-sisters (not by blood though)

And you probably think Star and Moony are besties and-

WRONG

Star doesn’t get along with Moonshine at all. Even though she doesn’t suspect it, I could say Star hates moonshine and the role she’s taken in her life.

First, Star has some kind of abandonment complex because of her parent’s divorce, she probably thinks it was her fault or something? Maybe she could have done something so they wouldn’t split up? Maybe? Nah, wasn’t her fault and nothing she did would have changed anything. If Twi and Flash would have stayed together for Star’s sake their family would have become miserable.

Then, Moonshine’s born. Star suddenly felt… replaced. As if her dad had abandoned her and her mother (fuck no, Twilight’s her godmother for fuck sake, no one’s abandoned except your screwed mind, Star). If stealing her daddy wasn’t enough, Moonshine’s a “little-miss-perfect” pink “princess” and has amazing magical skills (uh, of course, she’s Sunburst and Starlight Glimmer biological child, duh, and c’mon Star, u also have some freaking good skills), so that Twilight “adopted” Moonshine as her student, Moonshine and Twilight get along so well that you could call them mother and daughter. Which is the complete opposite of Star’s relationship with her mom. They argue a lot because of their different plans for Starswirl’s future. The worst situation was when Twilight ended up and argument saying “Why can’t you be more like Moonshine?”

that hurt.

Oh also Star says her hate towards Moonshine is due to “THE BITCH IS FUCKING YOUNGER AND TALLER THAN ME”