Thread:TheDigger1/@comment-27109830-20170318195723/@comment-26220697-20170320164349

Zen-Aku vs. Duskmon: Corrupted warriors who used to be members of the same group as the main heroes before they were turned to the dark side against their will, with Zen-Aku being a former defender of Animaria and Duskmon being a Legendary Warrior who was brainwashed. Around the middle parts of their respective series, they come in as the newest servants of their series' respective Big Bads, and quickly show that they're the strongest members of the villains' teams by thrashing the heroes in almost every confrontation they have with them. They both wield blades as their primary weapons, along with an assortment of dark powers. In their corrupted forms, they lack the memories of their former selves, until their defeat, which has them breaking the spell over them and becoming heroes once again.

Merrick and Koichi's connection is basically that they're Zen-Aku's and Duskmon's uncorrupted selves that join the heroes after freeing themselves of their corruption.