Angnyeonimui Choeaero Gantaekdoen Sajeong

Story

I’ve been reincarnated as Lariette, a lowly sidekick destined to be the female lead’s errand girl. Tired of being a doormat, I decide to switch sides and suck up to the empire’s most powerful villainess, Evangeline. But the “vicious” villainess is actually a total sweetheart! Not only is she showering me with gifts, she’s now insisting I marry her brother so we can be family forever. There’s just one problem: her brother is the original male lead, a man supposed to be obsessed with the original heroine. I’ve tried my best to keep my distance, but he won’t stop pursuing me.

Synopsis via AniList (English).