She later appears in Single Cell Anniversary. In this episode, it is Karen and Plankton's anniversary. Karen has accessed the Krabby Patty Secret Formula and is willing to give it to Plankton if he gives her something. Plankton leaves. Later, SpongeBob notices that Plankton needs help and agrees to help Plankton think of something for Karen. Soon, they find out that she is a music lover. SpongeBob teaches SpongeBob how to sing. Later, Plankton sings a love song for Karen with the help of SpongeBob and Patrick. As promised, she starts downloading the Krabby Patty Formula. However, she starts crying, which she is not supposed to be able to do, and she short circuits. She turns on again, but instead of showing Karen it shows "E.M.I.L.P." Plankton asks what that is and the full title shows up as, "Emergency Mother-In-Law Program". His mother-in-law then shows up on the screen and complains about Plankton.
Fredrick - Husband
Karen Plankton - Daughter
Sheldon J. Plankton - Son-in-law
"Plankton, what have you done to my daughter?! You made her cry! You know, she could've been with an ATM, someone with money, but she chose you! I don't know why!"