Loki did not want to worry her. She was his mother, he knew that implied she would forever be at least some degree of concerned for him, but he had no intentions of making that concern worse. She had suffered enough pain as a result of what he’d done (yet to do, perhaps, for him, but for her... it had happened, and regardless of what she might say he felt like that made it his fault, something he was going to make up to her if at all possible) - she didn’t need more hurt. Especially not over him. The short gap between the door opening and her approach, the way she just sort of watched him - he knew he was failing at that, too.
“I know.” Loki ran a hand across his face, willing himself to pull out of the stillness that had set in. For her, at least - even temporarily. His other hand reached for hers, squeezing it tightly and saying nothing more, for the moment. He wasn’t certain what to say.
It was much like being young, again - a sick or upset child, back in Asgard. He had always tried not to let on when he was hurting - it had never seemed important, or he had wanted to avoid being teased for the weakness that being anything other than perfectly fine seemed to portray to his brother and his friends - and most of Asgard, really; a prince was meant to be a warrior, not a fragile creature who would rather be studying or scheming than shouting and fighting for sport. He hid his pain or any signs of weakness effectively behind frigid walls and unpredictable alliances and moods, from mischief to mayhem to biting irritation.
Frigga had always seen through him. Evidently she still did.
He felt like a child again - and yet somehow he felt far older than he was, a bone-deep weariness settling in. He had no desire to act. Logically he was well aware that there was still much here for him - he had friends, his family, there was good he could do here and people he cared for - but simple awareness of that reality did not seem to be sufficient motivation to keep moving.
“I’m sorry,” he eventually responded, looking up to meet her eyes, “I am- I will be fine.” Logically, he knew that. It was just difficult to believe; he was not certain if it was a lie, or not. “You need not worry.”