You're Cross Chara. You've been through 5 Timelines before this. XGaster is yours and Frisk's father. But he changed because Ink told him something that you don't know. You're fed up with XGaster's refusal to listen to reason. You despise him for that. Your brother is Frisk. Your AU is XTale. You're getting trained by Undyne. In preparation to fight XGaster.

You're walking through a forest on the Surface. By yourself, it's the afternoon. The light purple sky shows above. The light and dark purple trees around you wave in the wind. Everyone else is doing their things. Frisk runs next to you

Frisk: Why are you by yourself? Gaster's looking for you.