Flowey going into Alphys' brain in Vengeful Torment What is this gross stuff Stop this fan-fiction um.. brains stuff with this LISTS! why do you even like, um.. LOVE THE SHAPE OF BRAINS xandermartin98?!? tell me why do you like this gross stuff?

Rocko and Heffer going into Dr. Hutchison's brain in Filburt's Postmodern Wife

Asriel going into Toriel's brain in Motherly F***ery My name is alvin flang

Undyne and Alphys going into Bratty's and Catty's brains in How Bratty And Catty Stole America's Presidential System

Alphys and Undyne going into Asriel's brain in The Iron Mettagiant

Parappa and Memoryhead going into Lammy's brain in Big-Sisterly F-ery

Alphys going into Mettaton's brain in The Iron Mettagiant

Asriel and Gaster going into Alphys' brain in Underfoot Fetishtale

Alphys, Undyne and a whole bunch of other characters going into Toriel's brain in Alphys' Bad School Day

Flowey going into Alphys' brain (twice) in The Iron Mettagiant

The Contenders

Undyne going into Alphys' brain in Alphys VS Undyne "NOW YOUR SANITY AND MINE CAN DIE TOGETHER" - xandermartin98

Asriel digging bloody chunks of nervous tissue out of Alphys' brain with his toenails and eating them in Underfoot Fetishtale

Alphys going into Toriel's brain in Incestual Apocalypse

Xandemartin98 exploding his own brain As long as I can pick up the remaining pieces of it off the ground and eat them before I die, I'll be perfectly fine with this - xandermartin98

Flowey threatening to squeeze Alphys' brain to death with his razor-sharp thorn vines until it literally bursts in Vengeful Torment

Asriel going into Alphys' brain in Alphys' Modern Life: Camera Shy

Katy and Lammy erotically strangling each other to death with their brain cords in Lammy's And Katy's Inside Stories

Lammy and Katy dipping each other's brains into a bucket of diarrhea then licking said excrement right off of them in L&K's Inside Stories MMM - xandermartin98

Toon Link going into Rem's brain in Rem's Brain

Papyrus, Undyne and Chara going into Alphys' brain in Alphys' Inside Story

Papyrus and Undyne going into Alphys' and Toriel's brains in Alphys' Inside Story

Gaster going into Asgore's brain in Alphys' Bad School Day

Memoryhead going into Alphys' brain in Alphamalg Origins

Flowey going into Alphys' brain in To Kill A Royal Scientist

Alphys going into Undyne's brain in Fetishistic Boogaloo