Sam saw Frodo for the first time at night.
He had settled himself down to sleep between the roots of a large tree; out here, beyond the Shire, trees were all so much larger than he was accustomed to. This night was the first night since he had crossed the river to escape the Urukhai, the first night he was spending alone. Without his companions, the air seemed so much darker- every little rustle was a possible threat, and for this Sam did not sleep easily. He would find himself drifting off between thoughts and then waking again, an aching cycle that continued until those thoughts made little sense, and he felt uncomfortable all over, and dreams began to invade reality.
So he thought it was a dream, when he saw Frodo.
It was an enchanting sight, the way Frodo stood on the path in the moonlight, and that moonlight seemed catch on him and make him glow. He was wearing a loose white tunic- made of some flowing material, so light and delicate it looked like moonshine itself- and comfortable traveling pants. He carried nothing, his hands folded lightly behind his back, and his skin looked as white and flawless as new snow, his dark hair clean and somehow halo-like, with how perfectly it settled around his ears. He looked beautiful, in short, so beautiful Sam could have cried, were he not certain he was asleep. He was reminded of the traveling band of wood-elves they had seen just beyond the Shire- a wonderful sight that had been, just like this one, and equally ethereal.
Frodo stood there on the path a few moments, peering into the bushes and out through the trees, like he expected to see something. Someone, maybe. But Sam made no move to reach out to him. He was certain that if he stood, or called out- or even blinked- Frodo would disappear, and Sam might never see him again. And that was the last thing he wanted.
So Sam watched quietly from where he lay for a while, until Frodo left, and when he did he took all of the moonlight with him, and the remaining night was dark and cold and empty.