So his pup wants to take mortals with him to Jotunheim. He includes the other two as well as the one that he can smell as bonded with his pup, even if it might not by physical yet, because he has no reason not to.

He stood and shook himself like the human equivalent of a very beleaguered sigh, and opened his mouth to howl. None but Steve would understand what that howl meant, what the words in the language were.

"Heimdall, Watcher of Asgard, inform the prince that Fenris of Jotunheim would speak with him on Midgard, if he is amenable."

Then he switched back to All-Speak for the sake of the mortals, at least two of who looked incredibly creeped out from the eerie howling. "He will come, of that I am certain. Be respectful. Though he may be a boor, he is the future All-Father."