It was a different telling of the movie verse where the Red Skull was the mastermind and was controlling Loki. Thor and Jane get married in Vegas thanks to Tony and I think Steve goes hunting with Thor's friends? I think Clint and Darcy end up together and Tony gets kidnapped and ends up staying with Loki using really old computers as he's forced to build something for Red Skull in a safe bomb shelter Tony's dad made? And Loki's teaching him magic that the women of Asgard learn so he paints his nails with a pink highlighter.
I hope that's enough information and I'm not mixing 2 fics up, I believe it was around 103k words because I misread it as 10k and ended up staying up all night reading it.