As Sunset escaped to the human world one of the guards accidently breaks the mirror, with the only way back destroyed Sunset finds herself unable to exact her revenge on Princess Celestia.

While this has put a stop on her plans she decides to make the best of what she has.

She only brought a few small things but what gave her a good head start was her bag of gems she brought, in Equestria they were common but she found out how valuable they are in the human world.
She bought a good house which gave her the privacy she needs and access to other stuff she might need.

Currently she's playing the nice girl at school just to scope out the situation, she then spots someone she likes.
Someone she wants to make her obedient slave.