THANOS: HERE TO FUCK SHIT UP
EVERYBODY: Wait! Loki knows this guy! AND Loki keeps on saving our asses, even though we're consistently complete ingrates! Let's ask him for some intel and consult with him on strategy!
LOKI: I thought you'd never ask. No, literally, I thought you would never ask. Here's everything I know about the asshole whose henchman tortured me onscreen for over a year. Also, Asgard's weapons vault has a lot of nifty toys in it which we could use to kick his ass, instead of, I dunno, leaving them on Earth for Nazis to find or for the Chitauri's master to use as a portal, or giving them to The Collector. Here, let's use them.
GOOD GUY #1: Thank goodness you didn't randomly morph into a villain since your masochistically noble behavior in your first three movies!
GOOD GUY #2: Or spontaneously lose 100 IQ points, like everyone else in Asgard did in between your first and third movies!
STEVE ROGERS: Of course he didn't! That would be as ridiculous as me joining Hydra!
ASSORTED SUPERHEROES: *use weapons from Asgard's weapons vault*