Strange man appears but why..

Well, this didn't happen to me, but to my brother. He had a room to himself, and he had bunk beds. He said one night (he was about 8) he felt cold and noticed his pillow had fallen off the bed (he always slept on the top bunk).

He rolled over and saw an apparition. He said it was a young man, dressed in a military uniform (branch unknown), and was dark skinned. He had his hands behind his back and was looking down, as if in prayer.

Zach was surprised, but not entirely afraid. He said he felt that he was safe even though he was seeing what he was seeing. So he decided he could safely retrieve his pillow off the floor, at the feet of the man standing there.

He climbed down, and as he grabbed the pillow, the man looked up at him. Zach said his face was peaceful, he was just watching what Zach was doing. Zach climbed back up the ladder and laid down, closed his eyes. He fell asleep and in the morning told me what had happened. He never saw the ghost again, but I always felt there was a "presence" in that house...