This was honestly the last thing Nathan had expected to find in walking in to Mantis' room, but he realized, after taking it all in, that he wasn't technically in the room anymore. Had this only been a room, this place would be incomprehensible to him because of the sheer horror of it all, but as a place of the mind, he had to step back from the surface of it and try to process what it meant. He knew, after all, what strange and horrifying places the mind held. Mantis was showing him this for some reason, a reason Nathan didn't yet grasp, but it was one he would try to understand.
He approached the table slowly, then moved along one side toward Mantis as he answered the questions. "You don't have to do that," he said quietly, as if afraid of disturbing this strange place he had entered. "Peter's strong, he needs a chance to try to suppress it."
Somehow it was easier to guide others when it came to Peter than it ever would be to take his own advice concerning his brother. If Nathan could have taken that power from Peter to save him that struggle, he would have done it in a heartbeat.
"I just..." He hesitated, uncertain of what he was about to reveal in continuing, things he had never talked about with another in this place so freely. "He has so many abilities. I don't know if someday it will be too much, but right now, I don't know how deeply this is gonna affect him, the damage it will do. He just up and leaves so much lately, even though he's making so much progress. You've seen how he is when he's angry, and it's more pressure. And I can't help him this time like I have before, because I can't touch him. I don't even know where he is."
He hadn't meant to say most of that, just to tell Mantis what had happened and ask for help in finding Peter, but there was a part of him that needed to weigh both sides, Peter's strength versus Nathan's fears of losing him again.