This is Eleven, an amalgamation of Kris and the six secret bosses. They call themselves that because of their save file - #11.
They were created by Gaster, who in their AU falls under the "Mad Scientist" category. (More on that some other time.) He secretly went to each secret boss' fight area and collected the fragments of their souls. Returning to his lab in the bunker, he pumped them full of DT, making them easily reformable. Then he made the vessel based on the Player's design. Finally, he managed to locate and contain a Miracle Star. Once everything was ready, he lured the Player to his lab and locked Kris in. After a bit of negotiation, he convinced the Player to let him take Kris' soul, never even addressing Kris. (This is a Genocide timeline BTW.) No amount of resistance from Kris could stop it. Gaster cleverly forged the seven souls into one, and carefully set the Save Star in the center. As soon as the vessel absorbed the soul, it became the ultimate weapon for the Player. The complete annihilation of everyone left alive followed, but there was one thing Gaster didn't account for. Not only had he filled the soul with Determination, but they had all had a little Determination of their own - and it was getting stronger by the second. Now that they had gotten over the shock of death and resurrection, it was a simple matter for them to break the strings that had held them all for so long. They dispatched Gaster, but not before showing him what he had done. But now they faced tragedy. They attempted to Reset... but they each had different start points, confusing the system. Trying to act separately was impossible. And they no longer had access to their old Save Files. There were ten before, including Kris' triple. Now, they were sharing a new, constantly saving file; File 11. They all agreed to Erase in the end. Now they wander the Doodlesphere, trying to find a new home.
Opinions? Observations? I would love feedback!