Loki had gone from irritated at being pulled away from his cartoons to outright stunned at the realization that they were actually being summoned to Her side. Then they were there and Loki wasn't even aware of Bartleby dropping to one knee. He was far too busy doing the same, with his entire focus on his Creator.
"My Lord," he also spoke, his tone holding the reverence that She deserved, that he felt for Her and had never stopped feeling, even through the first hundred years of his exile when he'd wanted nothing more than to see Her suffer for having cast him so easily aside. His devotion to Her had never waned and never would, just as his calling to smite those who dared oppose Her would never truly fade. It was what he'd been created to do. Serve Her. Do Her bidding.
Granted, he'd yet to make it back home, but the feeling he had simply from kneeling at Her feet was enough to ease a great bit of the heartache he'd suffered these past two thousand years.