Choose Me? ((Errorberry vs Swapfell)) ((Boy...
((Note: this is my first time using those AUs and Error! Sans. Please don't judge me too hard. -Sakura the Rose Knight ))
Underfell! Sans had always considered Underswap! Sans adorable, as well as everyone else. He was the only one he spared when his brother had forced him to kidnap the other Sans for intel. The same applied for Error! Sans. Underswap was the only AU he really wanted to spare, unlike the others. He wanted his blueberry to be happy.
But the two knew Underswap! Sans would only choose one of them, as his brother wouldn't approve of him choosing both of them. Or one of them, for fearing they would hurt his brother.