In a sort of role-swapped sequel to the infamous Giantess Alphys X Undyne scene from Chapters 4-6 of Alphys VS Undyne, Undyne shrinks Alphys to nearly microscopic size, allowing the two of them to finally exact their revenge on each other once and for all...using the absolute kinkiest methods imaginable.

And yes, the brain-infiltration part is also back.

WARNING: This story is so fucked-up that it actually makes the original scene it was based off of look rather TAME by comparison. Reader discretion and an extremely strong stomach are both very strongly advised; you have been warned.