Lovely!
I really like the minimalist narrative here. You bring a starkness to your descriptions that really fits in with the army-man approach to expressing both: fears and emotions.
I loved Snape here: He was firm, confident and maybe a little reticent. But he managed to respond to Harry's unspoken fears in a way that shows he cares. He came across exactly the way I imagine he'd be in this situation. He'd be the one man you'd like to count on, if you are ever in danger.