Erik's initial reaction to this was unreadable, as most of them were--whatever it was made him smile, but with Erik it was often hard to tell if the expression went all the way to his eyes. It was telling that he thought to be glad Raven hadn't tried to hug him or pull him in by the hands despite how effusive the greeting was, but--then he was pleased like he'd been the first time Sean had flown.
He wasn't present for much of the training regimen; that was Charles' specialty, and as far as Raven's ability went there simply wasn't much he could do for her. She had a control over minute aspects of shifting her appearance he could admire without envy, respecting it the way he would any gift that had taken years to hone with this much grace and ease. So what he passed to Raven when he had the opportunity was less definable, and generally abrasive. If someone (probably Charles) had taken it into his head to sit down with Erik and discuss the finer points of gently encouraging self-acceptance Erik would have had no idea what to do with it; gentleness was a thing that he had to for. In many ways he knew exactly what it was to hide even if his mutation was 'invisible,' - his parents once upon a time had hidden as best they could, and there was no shame in that. Everyone hid. It hadn't mattered.
So he was loathe to watch Raven's golden longing for a cure, and on that last night felt like he'd finally gotten somewhere. He nodded minutely, strange smile still touching his mouth (it did get all the way up to his eyes even if their color made it difficult to tell), and showed himself inside (....thank you, Erik), finding a chair to sit in. Erik dominated most physical spaces he entered without appearing to try, although of course that was practice too. It gave a person control, made the environment more manageable, and the inescapable fact was that he still considered these things in Raven's room where the mostly likely attack would come from like such terrible quarters as a pillow.
So he sat without direction, sitting forward on the chair with his knees apart and elbows resting on them, hands crossed loosely over them under his chin. "I came with Charles," he answered, assessing her 'normal appearance' from over his hands, "I've been getting acclimated." The use of acclimated spoke to nothing so much as justified bitchiness, but then his voice took a turn for the amused, gravelly as it was. "Now I'm checking on you. Seems justified to me, although I'm flattered by the enthusiasm."
He was, too! And trolling. A little. "Very clever, by the way. Her own parents would've been taken in."