Heartwarming / Dexter's Laboratory

  • When Dexter learns that pirates kidnapped his sister (they believed she was a mermaid due to her swimsuit), he goes straight to the pirate ship and reveals his Giant Mecha, which he had intended to keep secret, to save his sister, even though it would be easier for him if she were out of the picture.
  • In a weird way, the ending to "Beard to Be Feared", even though it's had some Memetic Mutation:
    Action Hank: "It doesn't matter if you have the beard on the outside, as long as you got the beard on the inside."
  • The first half of "LABretto" is really nice and funny, and then the rest is just funny.
  • The ending to "Dee-Dee's Tail". "Run free, Dee-Dee!"
    • Made even better by the fact that this one of the few genuinely happy endings in the series.
  • Dexter's duet with his piano teacher. Also doubles as Crowning Music of Awesome, because it's a sweet song.
  • Monkey getting Simian to do a Heel–Face Turn by offering him a banana.
    • Also, his memories with Agent Honeydew.
  • Koosalagoopagoop finally being accepted in The Land of Koos. The Tastes Like Diabetes atmosphere only added to the cuteness.
  • "Nobody bonks my sister but me!" Nothing annoys Dexter in the world more than Deedee, but messing with her will set off his Berserk Button in a way that messing with his lab has never accomplished.
  • The ending of "Sun Surf and Science" where Mandark befriends the surfer dude.
    • Also, him trying to save Dee-Dee.
  • Even though it's an Un-Cancelled episode, the story of how Dexter and Dee Dee's parents met back in 80s is pretty sweet.
  • In the quiz in episode 20 the final question is to identify each others favourite thing in the world. Dexter's is his lab but Dee-Dee's favourite thing? Dexter.
  • Dexter's and his family pulling together to defeat the Kaiju monster in the episode "Last But Not Beast" was surprisingly touching.
  • Dee Dee meeting Sasquatch in "Sassy Come Home" and the two becoming fast friends.