
I feel like what possibly happened was that after winning the bet Mc's wish was to protect Mimi by any means and that during the fall of ebis that Mc died protecting Mimi and Mimi on the brink of death demands to see mc again. The god seeing his soul is weak and feeling probably indebted to the mc grants it. Knowing Mimi soul would perish if not strengthened he tries to give a bit of his soul( like before with the mc) and realizes that it won't work unless he gives up all of his soul. So he does fusing their souls together and essentially granting the wish turning him to stone till mc found him again (I think rocky. Crumbed because anubis completely drained his soul and power)
Mabey rocky is a mix of aniubis and Mimi ? I'll explain later why I feel that but comment so I can remember I'm at work lol.