Merlin blew out the candle as Arthur asked, but despite what he had said, Arthur didn't end the conversation. There was a bit more back and forth, about Merlin's life in the village and what he was seeking in Camelot. At some almost-awkward moment, when Merlin almost wanted to tell Arthur about his secret and paused, at war with himself, stuck between believing Arthur was a true friend and the fear of dieing under the axe, Arthur again pawed Merlin's face with his foot. This time, though, Merlin grabbed the other boy's ankle. Arthur wriggled his foot a bit, trying to shake Merlin off, but the warlock held on fast. Will's words echoed in his head. He was not just Arthur's servant, someone to be pushed and ordered around by the crown-prince. He was someone.
Sitting up, Arthur yanked his leg harder against Merlin's grip, grabbing Merlin's shoulder in an attempt to force him to submit. This yanked Merlin forward, his face ending up scant inches from the blond boy's. For a moment they were at a stalemate: Merlin refusing to let go, Arthur refusing to concede. Staring at one another, a fierce battle of wills played out; Arthur's stony facade against Merlin's more expressive one. For the first time, Arthur saw the true strength the other boy held, a strength to match his own. Merlin saw the same thing, though it was strength of a different type that he beheld.
At this simultaneous realization, another thing became apparent. Merlin slowly let go of the still-grasped ankle as Arthur removed his hand equally slowly from the shoulder it was clenching. Both eased themselves back down to where they had been before the silent tussle. Both knew that the crowded sleeping arrangement they were currently in precluded acting on this sudden epiphany.
**
The next day, they both tried to act as if nothing had changed, as if they themselves hadn't changed in the night. It was hard, but the stress of the current situation made it easier. They had to focus on the task at hand. An entire village was at risk, and with it the fate of the tenuous bond between two kingdoms.
Merlin could see the bags under Arthur's eyes, wanted more than anything to soothe that worry. That was really what made him make up his mind. Not the voice of an old friend in his ear, and not even his own loyalties and guilt at leaving them. Only his pain mirrored on Arthur's face truly convinced him to do what he had to.
He knew it was a risky decision. Despite the moment they had shared, Merlin couldn't be certain that Arthur wouldn't turn against him. Even though he had seen, many times, Arthur act on what he felt was right, no matter his father's wishes, Merlin still wasn't sure that this wouldn't be the straw to break the future king and destroy any chance of exploring the bounds of their recent discovery.