[Papyrus fidgets his hands together, abashed and still a little unaccustomed to... this. Talking seriously and calmly about things, with a boss or adviser who doesn't brush things off with a bad joke or suplex him out of the blue because things are too serious.]

He... died.

[He frowns at himself, and shakes his head.]

Wait, that's not... taking enough responsibility.

I killed him. I...

...I even meant it. Kind of. And, while I remember now, he has an egg? It's still... I still hurt him, very badly, and that's against the rules. And you should know.

[Rather than find out from Joker, or Yuzu or Gongenzaka, or anybody else who's found out.]