Maybe it's the dog look? Cats and dogs are kind of the classic enemies... [Momo circles his own face with a finger to indicate he means the shape of Papyrus' skull - canines have fairly distinctively shaped skulls even without the fleshy bits, so maybe the cat caught on.] But I'll keep it in mind just in case I don't find a bond so quickly.

[He's not exactly planning to bond until he has to, but this could prolong things a little longer for him.]