Before Thor left, Heimdall let Thor know that there were many dark elves on earth. There is one ship of dark elves on earth. Heimdall discovered the dark elves only because of Thor's scientist friends on earth. Heimdall cannot physically detect the Dark Elves because they don't have souls but science can detect them.
Years ago, Thor made sure that Heimdall kept on eye on his scientist friends; Jane Foster, Darcy Lewis, and Erik Selvig. Thor met them when he was on one of his missions on earth. So as Heimdall was checking up on them, he found out about the dark elves through them. He knew Thor needed to go there as soon as possible. Asgard has a history with the dark elves.
Thor was sent straight to the location where the dark elves were detected and started fighting them before they hurt anyone. He was able to kill a few of the elves but eventually they fled from the scene and their ship disappeared. He knew the only way to find the dark elves now was through his friends. Thor found Jane and Darcy relatively fast with the help of Heimdall who helped him see where they were
Thor: Jane. It's good to see you.
Jane: What are you doing here?
Thor: I need your help. You discovered creatures called dark elves. The earth is in danger.
Thor, Jane, and Darcy go to Jane's apartment. They meet Erik Selvig there as well. The three of them are going to help Thor find the Dark Elves as fast as they can. They were able to do it once, they can easily do it again.
Jane: Anything?
Selvig: They are in Greenwich.
Thor: Let's go.
Jane: Thor, we have to figure out a way to get rid of them for good. Going to fight them now, risks them disappearing again. We might be able to make a device that makes them all disappear all at once. Give us a few hours, and I think we can create this device easily. Then we can go to them.
Thor: Okay. I'll be ready.
The next morning, Y/N goes to see Loki in the dungeon. She's finally going to let him out of his cell. Y/N can't wait to actually be able to touch Loki after all this time. All she wants is to be in his arms. She wanted to visit Loki and let him out as soon as she got Thor's blessing but sinceThor left for earth, Y/N had a lot to take care of. She's extremely overwhelmed with everything but the only thing that she wants to do today is spend time with Loki.
Y/N: Loki, my love. I'm sorry I haven't been down in awhile. There's been so much going on. Especially with Thor and I.
Loki: He came to see me. We talked about everything. But in the end you two are still married Y/N. Everything being out doesn't change anything.
Y/N: Thor and I are separating from our marriage. We can be together Loki.
Loki: How? I'm stuck in this cell for now. Or have you finally found a way to get me out of here?
Y/N: I'm here to let you out, darling.
