Basically at the end of Avengers when Thor and Loki are going back to Asgard, the cube/transporter thing was set for 2 Asgardians and not 1 Asgardian and 1 Jotunn. Loki gets booted from the transportation and is stuck on Earth. I think there was also a huge time difference. Like 3 months was a coupls days/hours on Asgard. I think at the end they finally get communication and Thor Dark World happens and Thor is asking Loki for help becuase Frigga already died? I think Loki was initially sniping at Thor about spending the time feasting or something. I hope someone recognises the fic?
Also, Im looking for good recs where Loki tries to commit sucide (again). Bonus if found by Avengers. I beleive there was one where they tracked him to some really crappy run down appartment block and found him bleeding out on the floor.