Napstablook is the role of Sans in Underturn.
He is very lazy and punny. Despite his liking to puns, he prefers pranks. He is depressed, but rarely shows it. He is open to make new friends, and will openly accept the protagonist. He loves his cousin, but loves slightly less to prank him. If his cousin is killed, he is very vengeful and observant. However, it isn't until the protagonist truly commits assetric genocide that he fights.
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