The story follows Steven’s 14th birthday celebration at the barn. The conflict begins when Greg reveals to Connie that Steven is 14—a shock to her, as Steven’s physical appearance has not changed since he was eight years old.

In Steven Universe Season 2, Episode 26 (often cited as Episode 22 or 23 depending on the platform), titled the narrative confronts the biological and existential complexities of Steven’s half-human, half-Gem nature. Episode Summary

Disturbed by the realization that he may never age like a human, Steven attempts to use his shapeshifting powers to "force" a growth spurt, appearing as a teenager to match Connie's expectations. However, maintaining this form is physically taxing. After overextending his powers, Steven’s body "crashes," causing him to de-age into an infant. He only returns to his true form after Connie reassures him that she will be by his side regardless of his age or appearance. Steven Universe Review: S2E23 - Steven's Birthday