[ The idea that the human of their pack, as ragtag and dysfunctional as it is, is the one that finally takes the step to actively join it is not lost on Derek. He continues to stare at Stiles as he speaks, that same (vulnerable) expression on his face. But it starts to steady, starting at the edges, as his jaw tightens and his brow knits together just slightly. It's not a disgruntled or irritated look, but rather a more serious one as he lets everything settle on him.

Here, in Arcanarum, he isn't a wolf as he was in Beacon Hills. But the sense of pack, the wolf's instincts, were never so much a part of his senses or abilities as they were simply him. His need to help the members who make up his pack remains as strong as ever, and actually hearing Stiles say I need an alpha is as strengthening as it would be if there was that almost tangible bond. ]

We might not know everything, but working together we'll be able to figure it out. And while we're all together, nothing will happen. To any of you. [ He tips his head forwards, towards him, keeping his eyes as he does. ] I won't let it.