Thank you very much for coming back to comment: it's probably a bit more difficult than commenting immediately.
I know what you mean about the Snape-befriends-animal stories: there's a danger of making Snape too friendly or fluffy. I'm so relieved to hear we dodged that particular bullet!
As for Harry treating Snape as his touchstone of familiarity - I think Harry's starved of touch (as is Snape, but unlike Snape, Harry hasn't yet learned to avoid it).
I'm so glad you enjoyed our story so much! Thanks again!