To say Thomas was expecting what happened next would be blatantly denying the obvious. He had expected some kind of offer, a Faustian bargain in which he gained power but was forced to betray the group, or consigned his soul to eternal suffering, or something like that. That was what usually came from accepting offers for help, or power, with evil people, wasn't it?

So he wasn't prepared as the man suddenly appeared behind him, earning an impressed thought or two about how he did that, if it was speed at a ridiculous level, which seemed unlikely given that there was no wind to indicate he had moved, so he must have a very powerful teleport spell of some kind. Then he wasn't in a position to think about that as a rain of blows hit his armor in all it's weak spots, feeling like a jackhammer to the limb beneath it, as it would have even without the wound radiating pain through it. Magic immediately rushed to reinforce the armor, but it wasn't enough, and it vanished in a flash of light to reveal the limb beneath.

He almost had to look, and his eyes widened at what he saw. Despite the man's prediction, it still looked human, which was a small favor, but black veins radiated across the entirety of his arm, black liquid dripping down and tinting his fingernails black. The wound rippled and pulsed, almost like it was a living organism, the skin of it emerging with small bumps that seemed to rise and fall, though it might have just been his imagination. Definitely not the most pleasant of sights, and his mind reeled from just looking at it. "Okay, you opened it, congrats," he said somewhat sarcastically to Mr. Mystery man, given that he couldn't do that himself. "Now what? You gonna try and convert me into some Heartless hybrid thing, or you gonna get rid of it?"