Okay what about an Undertale Mario AU where Mario is the Frisk there. So basically Bowser managed to take over the Mushroom Kingdom, and banished Mario and Peach to the remains of Bowser's castle. Sans is an OC character called Shade the Shadow Troopa (a Shadow Troopa is a Koopa Troopa with dark powers). His brother is Umbral and they have Dry Bones forms they only use when they have to. Bowser is Asgore, Peach is Toriel, and I haven't thought of anything else. (This AU is in between the Undertale and Mario timelines, but is closer to the Mario timeline.)
