|First airing:||October 14, 2005|
|Sister episode(s):||Mermaid Man & Barnacle Boy VI: The Motion Picture|
|Storyboard director:||Luke Brookshier|
|Animation director:||Andrew Overtoom|
|Technical director:||Vincent Waller|
|Supervising producer:||Paul Tibbitt|
- “I don't even know her name and yet she's stolen my heart.”
"Enemy In-Law" is the first segment of the seventh episode of season 4, and it is paired with "Mermaid Man & Barnacle Boy VI: The Motion Picture." In this episode, Plankton falls in love with Betsy Krabs, much to the dismay of Mr. Krabs.
- Sheldon J. Plankton
- Karen Plankton
- Eugene H. Krabs
- Betsy Krabs
- SpongeBob SquarePants
- Squidward Tentacles
Plankton uses a robot to take handfuls of customers and drop them into the Chum Bucket. They realize the scheme and leave the restaurant. Karen mocks Plankton for his failure, making him think of her as a nagging software. Meanwhile, at the Krusty Krab, Mama Krabs asks her son to lend her money for a hat, only to push her out before he has to pay. Plankton sees her through the window and instantly falls in love with her.
Karen notices and gets angry at him as she's his wife. However, he says she's just a computer and then turns her off. Later, he uses his robot to take Mama Krabs and flatter her, but his attempts cause destruction and she gets scared, until he crushes a rock into the shape of her. He then calls her to tell her they should meet face-to-face, and they agree to go to the Krusty Krab.
Later, Mama Krabs tells Mr. Krabs she has a boyfriend, which gets him excited as he won't have to handle her finances. She says she's meeting him here tonight, so he opens the restaurant late for them to have a romantic dinner. At night, they have the date, only for Mr. Krabs to realize Plankton's her boyfriend and tries to kick him out as he thinks he has a scheme. However, his mother stops him and they leave together.
The next day, Mr. Krabs tells Plankton to stop trying to get the formula out of her, but accidentally reveals she knows what it is and that his whole family knows. Plankton uses his new knowledge to propose to Mama Krabs to become apart of her family. Mr. Krabs sees and tries to stop her, but she declines on her own.
Plankton thinks she has someone else, and soon after his robot comes in with flowers. He can't believe this and asks her for the formula to make it even. Mama Krabs thinks he was in it just for the formula and punches him to his restaurant, where he accidentally turns Karen on again. She zaps him after he says she came crawling back to him.