Avengers: An Unexpected Encounter

(New York, nothing foreshadows trouble, everything is calm, everyone is busy with their own business, Tony is inventing something, Strange is meditating, Vision and Wanda are arguing about something, Bucky with his pet was sleeping on the couch, Steve was sitting next to him reading the newspaper, Thor was drinking ale and Loki was sitting in the library... everything was fine... until one moment... suddenly a portal opened in the training room and a guy with red-gold hair, green-emerald eyes and also in ancient Asgardian clothes of that time fell out)
Loki: Fuck...where the hell am I...? Is this another test from the Allfather...? (He muttered, rubbing his head after falling and getting up from the floor...the portal closed behind him...at this time in the living room)
Steve: (heard a noise in the gym, alert) Hey Buck...did you hear that?
Bucky: Mmm... (turned his head to the side in his sleep)
Steve: Ah... you're definitely asleep... sorry... (putting the newspaper down and going to the training room, taking his shield just in case) Hey! Whoever you are, come out... otherwise... otherwise I don't know what I'll do T_T