Re: Halt! Who are you?
"The astral plane, my friend," Heimdall told Thor, then summoned his steed from the outlook and clapped its flank so it would hurry to the Allfather. Their passage would be rapid but not to the detriment of Lady Sif's condition. "She has been in battle," he said, not just in body, was clearly conveyed.
Meanwhile...
"Thea!" Loki entered the infirmary, "You're needed... prepare for the worst, I'd wager. The Allfather left so abruptly he hadn't the time to explain the severity of the situation, but he called first for you. Grab your things, I'll bring you to him." Somewhere near Heimdall...