The Promise. (A MHA and Sans AU crossover.)

The multiverse is collapsing, and Nightmare is standing on the edge of Outertale's void, his teammates and his lover standing beside him. Error gently takes Nightmare's hand in his own, causing Nightmare to look up at him. "I promise, where ever we end up, we'll find each other again." Error says with a smile. Killer, Horror, Dust, and Cross all nod in agreement. Nightmare smiles. "Well, I'll see you all on the other side." He says, and they all jump into the pitch black endless void.

I got this idea by a discontinued fan-fic on here where the Bad Sanses and a few others fled to another multiverse to avoid Ink, who was the villain in the story. This will be an Error x Nightmare fan-fic, and will contain topics of suicide baiting, harsh bullying, and other such topics. You have been warned.