I think a really good way to avoid falling into this mistake is by starting from the ground up.
I'll use Jack interacting with Graviton as an example since I just wrote something for it.
So, I like to begin with an "Average Joe" viewpoint. To a guy on the street, Graviton is imposing, and some kind of fighter, possibly a Hunter or some other epic figure. He'd carry himself that way, and it would be pretty apparent that he either considers himself important or is important when he starts being bombastic. Now Jack actually is a highly skilled fighter, and he's familiar enough with what a Hunter is to get into Beacon. So he'd notice those things about Graviton even more. And because Jack schemes and knows that being socially mobile and having a wide circle of powerful allies/acquaintances is a good thing, he'll try and get on his good side.
Now what Jack would have no idea about is what Graviton actually is or what kind of power he wields. In this case metagaming would be Jack going "Sweet, time to buddy up to an Inquisitor!" instead of "Oh look, a Hunter at Beacon, maybe he can be useful to me some day, especially since he seems to be some kind of legal-ish guy."