War Diantha
From Fanonpedia
War Diantha
The Stealthy Warmonger.
After the death of Cynthia she starts crying red tears and awakens her Warmonger powers, choosing the warmonger life. She kills Looker in rage and crosses into the multiverse to start recruiting Champions.
Little does she know she'll go on a path to become quite like the monster of a Cynthia she once destroyed ✨✨✨✨✨✨✨✨
Is emo, likes to kill people. Technically an Apex but is quirky and has Red eyes instead. Powers include creating portals enabling travel throughout the Multiverse.
Would do an Undertale Genocide route.