Good fic uploaded by it's rightful author. Recommend people to check him out on Fanfiction or questionable questing if they want to read the rest of his works.

Stole the fanfic from another author (Flameclaws) and had the shameless of plugging their own Patreon to benefit from it. Don't recommend reading this here, from this author. Search the original author on Google.

So basically, Ei is Raikou from fate?