undertrap(sans)(you can make au versons of him if you want to)

Description: sans used to be a brother to papyrus,gaster would experiment with them,and he injected a large amount of DT in sans left eye causing sans to have the red glowing scar that runs down his skull,it was made so sans could not instantly get one hit killed,sans has ten hp and he still wears the science coat gaster gave him,however,sans tried to escape gaster again,and together with papyrus,they escaped to snowdin,where they lived for sometime,however,after a argument over who was "alphys" by a confused papyrus resulted...…...well,long story short:papyrus became captain of the royal guard and then sans and papyrus had a fight and that's how he lost his right eye(and almost the entire right side of his face) due to this injury,he can use only bones now and his blue magic is weaker then before,he does not make puns anymore and he later decides to join frisks journey to escape the underground,however,after frisk returns to snowdin to get her locket,papyrus returns to snowdin as well under orders from gaster to kill sans,in the netrual route,sans is killed,but not before restoring papyruses soul,but unwittingly causes papyrus to go insane on realizing he killed his on brother and goes on a rampage across the underground in search of you and you end up being forced to kill papyrus at the jugement hall,in the pacifist route,sans restores papyruses soul without dying and papyrus realizes what he has done and joins frisks journey not to help frisk escape,but to find a way to stop asgores oppressive rule once in for all,and in genocide,sans lures away papyrus from snowdin and tries to kill you beliving if he kills you,he will finally be no longer hunted,however,after 28 rounds of fighting him,you kill him,and go on to waterfallthis is his battle theme in the genocide route:https://soundcloud.com/darkronaut/anti-gztale-mel-theme-undertale-remix