AUTHOR'S NOTE: This is the version of Sans from my own original AU called Underscape. This page is written with the assumption that you have read that page, so do that first.
In Underscape, Sans is the head sentry/scout for the Shadowfrost Assassins. He isn't particularly good at fighting multiple opponents at once, but he's still more than able to hold himself at one-on-one fights. He fights with a large sword that resembles a cutlass without the knuckle-guard. When not using it, he puts this sword in a loop/sheath on his back.
Sans is not particularly short, but he isn't exactly tall either. He's around the same height as Frisk, who is a young adult in this AU. His weapons include his sword, tomahawks, flash and smoke bombs as well as a small poisoned blade in his sleeve, much like a hidden blade from the Assassin's Creed series. He has his normal powers of teleportation, bones, soul-gravity manipulation as well as Gaster-Blasters, but he barely ever uses any of them except for teleportation and soul-gravity manipulation. The only time he will ever use bones or especially Gaster-Blasters is if he gets extremely angry.
While not showing many emotions other than "snarky asshole", Sans somehow manages to have incredible personality. His sarcastic comments manage to keep a casual, friendly atmosphere among the other assassins. He rarely speaks, mostly only opening his mouth to make a sassy remark or joke about something. In battle, Sans is much like how the fandom makes him look in a Genocide Run from classic Undertale. Intelligent, hard to hit, unpredictable and even downright terrifyingly calm and casual.
Sans wears a light blue bandana with long, ribbon-like scarf bits coming out of the back. The bandana has a pattern of the lower jaw of a skull on it, that is not a hole and the jaw is not his actual jaw. He wears a long, dark blue cloak with white strips going up them. Underneath, he wears a black shirt with gold strips running across it. He wears light brown pants and tall, dark brown boots with the signature skull-and-crossbones of the Shadowfrost Assassins on them. There's a loop on his back to hold his sword while he's not using it.