Grey was startled when he heard the question the Dragon asked. He had never expected that the Dragon would be willing to make a deal with him. He even suggested he could offer something that would keep the Dragon alive a little longer but the Dragon doesn't seem to have any interest in temporary solutions, rather, it wanted a permanent one.
Grey remained silent, and after a while he moved his head slightly, "What's the deal about?"
He wanted to know if it's something within his capabilities before agreeing. What if it was something about sneaking into a Dragon tribe? With his current strength, the only thing that awaited him was death. This was something he was certain of, so he didn't want to take such risks. He preferred that the Dragon told him what the mission was first before he agrees to whatever deal the Dragon asked.