You were capture by the shield because you helped Wanda escaping from Westview, of course you and Wanda are sisters, but your her little sister. After Tony place you in your cell you happen to try and reach Wanda. But then you caught Loki on sight. He walked towards your cell and took a good look at you.
Loki:arent you a magneficent creature.
Y/N:release me.
Loki:and what?
Y/N:you'll get what you seek.
Loki:really?
Y/N:i can read your mind. Frost giant.
Loki:what?
Y/N:thats right. Loki Laufeyson.
Loki left and leave you there alone again. Loki didnt know what to do but he has a plan about it. He sence that he might have something to do with you and your super powers. During the hour, all avengers are out to a mission and it was only Loki and Dr. Strange in Stark tower to keep watching things around and you. You called for Loki and he heard it. He made his way to you now and got caught by some guards. He played it cool and made his way to you. When he made it to you, you already awaited for him. He walked closer and you smiled knowing that it'll work.
Loki:I heard you and your sister can control the dead.
Y/N:no. Not her. Barely. But darling we're not Agatha.
Loki:what hapoen if I let you go?
Y/N:im a word of my promise. You will get what you want by doing what I want.
Loki:fine. Deal.
Y/N:perfect.
Loki:where do we start?
Y/N:how about... Lets start by releasing me.
Loki unlocked you and the alarm was set off. You were free and you took Loki with you. You both went to the edge of new York and find a way to get to west view.
Loki:perhaps I could use a bit of magic on this.
Y/N:of course.
*THE AVENGERS
Tony:what do you mean Y/N escaped?
Stephen:Loki released her.
Tony:Loki?
Thor:thats not possible.
Clint:i thought he changed.
Steve:he started changing ever since we talked about Wandas sister and her powers.
Tony:we trusted him.
Thor:we can still trust him.
Steve:after what he did?! No way
Thor:look he is my brother.
Nat:we have to find out why he did this.
*WEST VIEW
You both made it to the borders and you noticed that Wanda is still not here yet.
Y/N:she is not here.
Loki:now I brought you here.
Y/N:but we arent done.
Loki:DANM IT GIVE ME WHAT I WANT!
Y/N:now now. Thats now how I work my promises.
Loki:what happen to what you said "your a word of your promises."