Sans doesn’t usually like children (humans or monsters), they disturb him and make him quite uncomfortable.
And Rosey was quite hard to deal with. They was overly sociable and way weirder ( perhaps dumber to the skeleton taste xD) than any kid Sans has met. But got quickly attached to him (no matter how much he’ll try to deny it).
A long time after gaining Frisk trust (which was really not easy), he often babysit the rose (for some money too cuz he’s still a greedy bastard).
