So the diagram actually isn't on the floor. It's on a table. The table is in a room with high enough ceilings that you can stand on top of the table if you so choose, but why would anyone do that? Chanai, who is alternately sketching the vaguely circular array he wants to use for a spell and using the space around the edges of the same paper for notetaking, is sure not expecting anyone to stand on the table. In fact, none of the people in this room are expecting anyone to do that.
Cam would not in fact usually choose to stand on a table, or expect it to come up, either, and yet here he is.
Damn, his canned line for scenarios that were never supposed to come up sounds so much less snappy if it's not on the floor.
"You summoned me? With the gigantic diagram you were so painstakingly drawing? Not that it helped, you could achieve this result in crayon."
"I took the summons voluntarily, I was just expecting to be summoned by someone who knew anything, at all, about what they were doing." He climbs down off the table.
Chanai (and Tyela who is now backed up against a wall) is so wary of getting close to the alien.
"Well, it's not my house to welcome you to, but I expect the person whose house it is won't mind if you stay a moment and tell us what just happened. I'd offer you something to drink and maybe a snack but I don't know what your species eats."
"I don't have to eat and can supply my own snacks if I want them." Tiny watercress sandwich. Nomf. "What happened is you drew a summoning diagram and it summoned me. Haven't you ever seen a daeva before?"
"That would be contiguous! There'd be a path you could take if you flew."
"Okay, interesting, I retract my complaints about you drawing a summoning circle, I think this perhaps isn't the universe I'm usually summoned to."
This is the point at which someone else enters the room. (She's actually been listening at the door for a while.)
"Hello, welcome to Zorvey and welcome to my home."
He makes a little model of the planet they're on to look at instead, with glass oceans.