you were the player, sort of, more like a guide for frisk. in here instead of full on controlling them, you simply guided them, helping with decisions, and helping in fights if need be.

it was nighttime, the both of you staying at the inn at snowdin. Frisk sleeping peacefully, while you were sitting at the windowsill, doing whatever, since you didn't necessarily need sleep. frisk just had a nightmare, but managed to fall back asleep after hugging sans's hand, or detached hand...copy? not sure how to describe it, but they had it with them ever since they met him yesterday.

some time would pass, and now frisk was asleep, and from the corner of your vision you'd see the soft glow of the hand again, which usually meant sans would use his true sight, using the hand to sometimes watch over and see if frisk was taking the right route, the pacifist one, which you two were.

sans in the meantime had just gotten home with papyrus, papyrus already in bed, while sans was at the couch, taking a 'nap' while using his ability to check on the kid again. This time though instead of just checking and that's it, he'd let his hand float over to you to see what you were doing, which wasn't really hidden, since the blue mist-like magic around it was quite obvious.