Deltatale is an AU where Asriel has turned evil and overthrew his dad, Asgore Dreemurr. Also making Chara his servant. He eventually takes Undyne into slavery, killing Chara.
After killing almost all the monsters, he gains the power of time travel. He travels to the future, and kills the other children, getting to an almost invincible form, after absorbing their souls. He then breaks the barrier, and attacks Frisk's village. Frisk returns from Mount Ebbott, after just barely not falling into the underground. When back, the town is in its ruins. Woman & chlidren are huddled, crying, and Men are trying to rebuild homes, while others lay dead on the ground. Frisk has to stop Asriel before he destroys the rest of the world.
- You play as Chara, (the spirit) helping Frisk in her journey.
- Papyrus wants to commit suicide, as Asriel killed Sans. So you must convince him to not through out the journey.
- Basically, Papyrus is helping you find Asriel. (And he wants to get Undyne back)
- Alphys is hiding in her true lab, inventing a battle suit for herself, but in her fight she doubts it'll work. Eventually giving up, handing you the right to kill her, or spare her.
- Gaster was killed in the past before Asriel time travelled.
- Toriel and Asgore live with Alphys, & stay in the underground the whole game.
- Toby is dead.