It's the the prickle of a five o-clock shadow that contrasts with the strands of soft hair that fall around Anders' face, and both that brush Nathaniel's skin. It's the chapped lips that remind them both of the high winds of the day, and can see the fabric of the tent tug in the corner of their vision. It's the sound of the wind and the crackle of the fire that gives them privacy - daring small gasps and whispers they would never chance at any other night while camping.
It's not the heat of the fire that Nathaniel notices but the warmth of Anders' body on his - skin sliding against skin in such a way Nathaniel is sure he will go crazy. It's the way his nails dig into Anders' back, and pulls him closer. It's the way they move together, and how any thought other than each other is impossible.
It's the way Nathaniel's guard lowers when only Anders is around - the way he does it without realizing it.