So. I’m not a fan of how sans and Toriel are characterized in a lot of Underswap aus, so I made my own. I won’t go into too much detail on it, BUT. She doesn’t really ever leave the castle, and hasn’t really talked to anybody in hundreds of years; leaving the underground to be ruled by a council of a couple of important people (royal scientist, captain of the royal gaurd, etc). Sans gets hired on to be her body gaurd as a favor from Alphys cause he’s low on cash. It’s a really easy job he just has to go stand outside the door to the thrown room for a while and chill. They do thier knock knock thing and get close. Eventually she lets him in and they become friends. As an extension of making the promise, he lets her knight him (AS SEEN ABOVE). Baisically promises he’ll help her out where he can and stay loyal to her if things go tits up.