What I remember of the fic went like this - Theres a random enemy that attacks the avengers. Hes strong af, able to take everyone down, but he doesnt cause any actual harm. He demands for the avengers + thor to bring him to Loki. Avengers + thor go to asgard. They find Loki being tortured in Agard by the alfather, enemy saves him.
Tony and Loki hit it off after Loki is rescued. Somehow or another, Tony becomes asgardian. Over the many centuries, tony fights alongside the asgardian army, he gets injured. He locks himself in his workshop and builds some mechanical legs(??) for himself. Ends up the enemy all those years ago is a Tony Stark that travelled back to save the man he loved.
Wow. I remember this fic really clearly, but I really cant find the fix anymore.. forgot the name... anyone heard of it??? :(