^ Was an earthworm in their past life. Did some evil stuff against other earthworms, died in a slightly too heavy rainfall, and bargained with some obscure earthworm deity to get back to life. It didn't work out as planned though, instead of getting back a an earthworm, they're now a human and has a contract from said deity to save other earthworm from natural catastrophes in an effort to get back to being an earthworm.
There's a big chance they might not uphold the bargain though since being a human has some benefits over being an earthworm.