So I found this really good fic a few weeks ago and I forgot to bookmark it and now I can't find it.
It was on AO3 I think, although it could easily be on more than one site and it was about Morgana, although everyone just called her Morgan placing mind control over Loki and then having him fight the avengers. Loki then works with the Avenger to try and destroy her. And there's an OC charater whose name I cannot remember who can turn into a cat.
I'm sorry that's not a great description but if you know what fic I'm on about please let me know, even if you just know it's name or something