Balerion Black and the Rise of the Dark Lords

The time was 1938.
Balerion Black had received his half-brother's torture since he first came into House Black. That is, until he finally snapped.
With a foreign soul with the knowledge of Harry Potter merged with him, the new Black set out to carve a world where the weak like himself were trampled no more.

Basically, an accursed idea about how fem-Grindlewald, fem-Dumbledore, and fem-Riddle is having a triangle tug-of-war with a poor boy's soul. Fun.

(anti-hero MC, 1920s)
(main heroine is Riddle)