Three grownass men, all not entirely the best at carrying trauma, all with terrible coping skills. Because Strange just does not want to talk about this. Talking about this would make him have to acknowledge things like just how damn scared he is: scared of Nightshade, scared that something like this will happen again, and scared there won't be any way for him to stop it.

As Childermass approaches, Strange stops fiddling with his sleeve and stops trying to roll his shirt sleeve back down. A brief look of confusion flits over Strange's face and a second passes while Strange just tentatively looks over at Childermass, not entirely sure what to do. And then, impulsive as ever, he decides screw it. Might as well let Childermass see the marks as well, if only to stop him from thinking things are worse than they are. With a small sigh, he sort of awkwardly sticks his arm out for Childermass to look at.

"The faeries," he answers, "or more specifically a faerie. That Portland idiot bargained my memories back but didn't take into consideration what Nightshade might do if she saw some of those memories. I was kept in her realm for a few days. She released me when the Rose Queen charged us to disrupt the ritual and bring Steven back. I was fully under her control at that point."

That's right. Childermass and Lambert were mostly unconscious for that part of the ritual, something that Strange is just realizing now.