ML took his sister place as the bride offering, surprisingly the God took him (cause he's GAY) unbeknownst to the fact the God actually cursed his family which lead the the "troublemaker" Heil stealing all of the brides (he's BB tho) but plot twist the God (Pain) misses his ex-lover and decided to exchange his bride for him (he was in hell) and Rivwr became a sacrifice for Shuyin, the river god, and ends up with Heil.
HeilxRiver
The God of Pain's Groom