Mr. Cake takes the twins, now wearing their new onesies, home from Rarity's. He thanks her and reveals that the reason Pinkie Pie can't foalsit them is because she's not been quite right ever since the Starlight-deer-horn flu incident. She will be given a boat trip which will hopefully put her back to normal, but that leaves the question of who will watch the twins since Rainbow Dash and Fluttershy have work and Twilight has to deal with Starlight. Rarity suggests one of the Cutie Mark Crusaders.
Mr. Cake notices Diamond Tiara at the sweet shop who reveals that she wants to have a chance to actually earn money because her parents are considering cutting her allowance. They offer to have her foalsit and she accepts, while the Cake parents go to a check-up.
The twins are surprised that Diamond is foalsitting them, but they're happy just the same, and she tries to play the "tickle monster" game on Pumpkin. However, this causes Pumpkin to accidentally zap Diamond Tiara.
She blacks out, then wakes up to find she's the same size as the twins and her voice is now higher and with a speech impediment. The twins reveal that she turned into a toddler but it's happened before with Gummy and never lasted, but just in case she's incontinent as a toddler they'd better put her in a diaper, but if she's not, she's welcome to share Pumpkin's potty. Diamond takes her transformation well as she sees it as a chance to have a toddlerhood without her mean mother.
This chapter provides examples of
- Angst? What Angst?: In-Universe, Pumpkin is surprised at how well Diamond Tiara takes being stuck as a toddler for several hours.
- Baby Morph Episode: Downplayed; Diamond Tiara turns into a toddler.
- Babysitting Episode: Diamond Tiara foalsits the twins.
- Big, Stupid Doodoo-Head: Diamond Tiara calls her mother a "poopie head".
- Formerly Fat: Implied. Diamond Tiara is described as chubby when she turns into a toddler, suggesting that she was chubby in her toddler years. As an older filly, she's average-sized.
- The Diaper Change: Discussed when Mr. Cake says that Diamond will probably not have to change diapers as the twins are in potty training.
- Power Incontinence: Pumpkin's magic sometimes goes haywire when she's tickled, which is what made Diamond Tiara turn younger.
- Suspiciously Specific Denial: Diamond Tiara says that she's not in Sugar Cube Corner just to find something to do.
- Temporary Bulk Change: Diamond becomes chubby when she's a toddler.
