Daniel feels incredibly lonely when he returns to the mountain. While he was in the village, he was able to spend time with Joel and Malthace, recuperating from his injuries. During that time, the three youngsters pledged their lives for Israel and to drive out the Roman occupiers. Daniel's experiences as an insurgent clearly haven't dimmed his revolutionary ardor, despite his narrow escape and injury. If anything, he's become even more enthusiastic about his political goals and commitment thanks to the encouragement and moral support he receives from the twins.
Daniel establishes such a bond with Joel and Malthace that it's not surprising that he feels so lonely when he returns to the mountain. The men in the camp treat him like a hero for a short while, but after that they go back to ignoring him. No wonder, then, that Daniel should feel so lonely and that he should want to return to the village to see his close friends and comrades as soon as possible.