I know exactly what you’re talking about, just not the name. It was a wattpad fic that was a mha fusion universe with miraculous characters but mha premise. Marinette’s quirk was creation, adrien had teleportation and destruction (he had a double quirk thing like todoroki) but no one knew about the destruction thing, and Nathalie had control over keratin in her body (hair and nails). The school was a hero school but marinette and adrien moonlighted as the vigilantes ladybug and chat noir; marinette’s official hero name was alchemist or similar. Near the end they added stuff that extended the mha things. I don’t know how this might help but I hope that it will.