A Captain Always Gets 'Revenge'

Undyne recruits Sans and Frisk to help her get some 'revenge' on Papyrus. Sequel to "A Tough, But Good-Hearted Warrior" and a bit of a sequel to "Prompt 16: House Chores" and "Revenge Of The Fish Captain". :) Done as a request for both Smileheart110 on DA and for The gay geisha's little brother. :)