"Uh, hi?" calls Cam. "I'm not gonna hurt you."
"You summoned me? I mean, it looks like you did it by accident, you should be more careful, but that's entirely on your end, dude."
"Well, perhaps we can help each other. Where I am from summoning is common. Accidentally summoning a demon with no bindings on much less so but it would be really, really weird for somebody to appear a winged person and have no idea what was going on. Also, religions which ascribe significance to demons and angels are still extant, if less popular and increasingly schizophrenic about how the summonable versions interact with their theology. Now, where the heck am I, please?"
"I am summoned to Earth more often than anywhere else, but I don't live there. What is a stargate?"
"I begin to think this is the sort of place you will be very glad to have a summoned demon handy. Who put the stargate there, why haven't they shown up to see what happened to it, any clues?"
"Lead the way."
Gas bags, hallway, stacks of food and other things in crates, hallway, control room completely devoid of electronics and mostly devoid of metal. Is that bone? Yes it is.
"What are the properties of summoned demons, anyway?"
"Well, if I threw something overboard it wouldn't be very hard to get it back. And not just because I could fly after it and catch it. Is that made of bone?"
"You are going to be so glad you accidentally summoned me," predicts Cam. "Demons: make stuff."
"What kind d'you want?"
"I don't. I live a life of perfect material luxury. Or to put it more exactly: I want something to do. Because where I'm from everyone lives a life of perfect material luxury and it means I'm a little low on fulfilling vocations."