Alphys

Main
Alphys is a character in Uppertale

Neutral/Pacifist
In the neutral/pacifist story modes, Alphys can be seen at her house. After meeting with Sans, she appears and asks the player to come with her to test her time travel machine. After testing the time machine and going back into the past at least once, she will ask if the player is done exploring. Say yes, and she will ask you to take a picture of her and Undyne smooching from before the fight with Asgore.

When you see her again after accidentally changing the past, she asks you to fix it by telling her past self to never ask you to use the time machine. Upon completing this task, you see Alphys and she has no memory of asking you to take the picture.