Hello there! Also no worries about Tumblr, I had no idea that you need an account to send in questions to the inbox so going forward I'll adjust my game development posts to reflect that in the Q&A section. :]
I can just copy/paste the question and block out your name if you would like to keep this anonymous!
This was a thoughtful ask to answer! :]
If the player(Y/N) suddenly did this to Noah, his facial expression and body language would all depend on how close of a relationship the both of you have with each other and what leads up to this. Noah likes his personal space but if he trusts you and there's a genuine connection going on, he'd be more relaxed/comfortable.
If the both of you are spending time together and being silly up until that unexpected moment he would be surprised at the sudden bold attempt. His eyes would slightly widen for a moment only to lessen as he fondly takes in the player(Y/N)'s features before closing his eyes and giving a sudden kiss. He'd then flirt with the player(Y/N) given their flustered expression only to let out a small laugh give a warm embrace. :,]
If the relationship is very distant and there isn't enough trust going on he'd quickly go on the defense and firmly tell the player(Y/N) to move and not to do that again.
In the [Extended Demo] there's a small yet similar situation where he does avert his eyes. The first time is when the player(Y/N) falls onto him after he tries to keep you from tripping backwards. He looks to the side while slowly pushing the player(Y/N) off since the situation is awkward, you're in his personal space and he doesn't fully trust you yet. The second time it happens leads to the player(Y/N) accidently stumbling into him against the hallway. This time he's bewildered at the unexpected interaction since the player(Y/N) is holding onto him. When the player(Y/N) looks up at him he averts his eyes a second time before asking the player(Y/N) to get off of him.