Thread:TheDigger1/@comment-27109830-20190515064204/@comment-26220697-20190815215023

Both are the younger siblings of the main protagonists who were greatly changed as a result of a horrible tragedy that affected their families, with Alphonse losing his entire body and being bonded to a suit of armor in the botched attempt to resurrect his and Ed's mom, and Nezuko being transformed into a demon in the same attack that killed her and Tanjiro's family. This led to their older brothers setting out to join a special organization, the State Alchemists and the Demon Slayer Corps respectively, in the hopes that it'd provide them with the information they need to return them to normal.

The connections aren't that great, but I've been really getting into Demon Slayer lately and this was the best idea I could think up.