Soul Fused

Nightmare, who has been dead for the last century, stumbles across a dying Sans in a destroyed au and takes him under his wing. Er, tentacles. From there, they start a band of rejects to get revenge on his brother. Sadly, said brother has other plans for them. That wont stop the shakily made team from bonding and having fun though!

(AU where Killer is the leader of the 'Bad Sanses'. I own pretty much none of the characters)