MadLust is an Undertale AU with a combination of ideas from Underlust and Dusttale. Sans lived with his brother Papyrus in snowdin, he was a sentry, and a pole dancer at Grillby’s strip club. Life was okay, but then the human showed up in UnderLust. The first couple resets were okay, until the human got bored. They slowed started to Rape and attack monsters, driven by Deterination…and Lust. Sans tried to stop the human with mercy until they attacked, raped and killed his brother for the first time. That’s when Sans attitude changed, and they after hundreds upon hundreds of resets filled with Rape and Murder, Sans couldn’t take it anymore. He could no longer sit back and watch until the end. His quickly unravelling mind came up with a plan, he needed to keep everyone safe and decided to kill them all himself. Giving them all a quick death to them from the pain and torture of the human, which would also give him enough LV to kill the human easily. He doesn’t save Papyrus to last however, Papyrus was the first. He didn’t want him to see what he was about to do. Papyrus at first didn’t fight back but just as Sans was delivering the final blow. Papyrus lashed out hitting Sans hard on his right side, shattering his eye socket and jaw. Sans used Papyrus’ horrified shock to his advantage, but Papy’s final words haunts him.. Papyrus’ death at his own hands completely breaks Sans. He continues his mission however filled with determination, feeling no guilt, only conviction. After Papyrus, killing other monster was a lot easier, his goal firmly set in his mind. Once every monster in Snowdin, Waterfall, Hotlands and New Home was dusted, Sans headed to the Ruins killing his way through, not even Toriel a second glance as he dusted her. His eye lighted firmly set on the Human. They were about to have a 'Fuckin' bad time.' Starting a new cycle of killing. He will 'Protect' everyone from the human, no matter what. (UnderLust and Dusttale belong to their creators, they both just gave me this idea.)