“Marvel’s Agents Of S.H.I.E.L.D.” Season 2 is planning another exciting Marvel Cinematic Universe crossover. Lady Sif (Jaimie Alexander) from “Thor” will make her second appearance on the show, TV Insider reports. However, this won’t be a pleasant reunion. Although Lady Sif guest starred in Season 1, it seems she won’t remember the S.H.I.E.L.D. team, or even Thor. The Asgardian warrior will be dealing with some memory loss.

“Sif can't even recall who she came here from Asgard to stop, but Agent Coulson [Clark Gregg] and his team will try to help her figure all that out," executive producer Jeffrey Bell said.

Who is Lady Sif fighting? Her enemy is being kept under wraps for now, but Marvel probably wouldn’t be so secretive unless there was a fun surprise for comic book fans. We have a few theories as to who she may be fighting:

The Executioner and the Enchantress: The Executioner was an Asgardian warrior who went through a period of time where he was Thor’s enemy, according to Comic Vine. He and the Enchantress actually teamed up with humans to take Thor down, so that would explain his presence on Earth. 

Destroyer: Despite being created by Odin to help Asgard, the Destroyer is one of Thor’s major foes and actually has a big storyline with Sif in the comics. The Destroyer, a mystical being, manipulated Sif and they ended up fighting Thor together. While a throw down with the Avenger certainly isn’t in the cards, that doesn’t rule out an appearance from the villain.

Mojo: This Marvel villain appears in the Longshot comics and X-Men comics, but that doesn’t mean he can’t show up in “Marvel’s Agents Of S.H.I.E.L.D.” Mojo is one of the Spineless Ones. Without a spine, Mojo has to rely on mechanical devices to move, according to Marvel. He also has erased memories before, which would explain Sif's memory loss. While he typically lives in Mojo World, the ABC drama has been known to tweak comic book mythology. Plus, Mojo has a method of transporting people to Earth and back. He sent Longshot to capture the X-Men, a plan which obviously failed. Mojo could be jumping between planets or sending someone on his behalf to capture powerful people like Lady Sif.

Loki: We can dream, right? Loki (Tom Hiddleston) made his screen debut in “Thor” and was the main villain in “The Avengers.” The trickster is probably easily capable of erasing memories, but he might be a little too famous for the Marvel TV show.

“Marvel’s Agents Of S.H.I.E.L.D.” Season 2 returns to ABC on Tuesday, March 3 at 9 p.m. EST. Who do you think Lady Sif will be fighting? Sound off in the comments section below!