Kili could scarcely believe it when Thorin began to accuse Saeril again. This couldn't have been farther from the truth; she had only tried to warn them about the dragon sickness. Thorin's behavior was unlike him, and Kili began to wonder if the Arkenstone would fix the problem. Saeril had cautioned against this too, however. If Thorin did not have the Arkenstone, he would go mad searching for it. If he had the Arkenstone...would that quench his desire for power, or would he seek more of it?
Kili allowed his brother to pull away, relieved that he'd chosen not to fight. Fili was wording things better than he would have, he was always so sensible and levelheaded. The mention of their mother was a wise move; Thorin was snapped out of his rage long enough to see a bit of sense.

The king stared at Fili as he spoke, and for a moment, it was as if he did not recognize the blond before him. Slowly, the words sought their way into his rattled mind, and he looked towards Kili, shocked to see the bruise on his face[i]. Dis would have been outraged.[/i] The thought of his sister was enough to silence him, a heavy pause lasting a short about of time. 
"We must continue searching," Thorin's voice was weighed, heavy from loss of sleep, and possibly even guilt. This only lasted so long before he seemed angry again; he was completely unpredictable, and that was what made him so dangerous. "Tell me the truth, both of you. Does she know where the Arkenstone is?"