Ep 12. Steven's Birthday / It Could Have Been Great

In Steven Universe season 3 episode 12, titled "Steven's Birthday / It Could Have Been Great," the Crystal Gems prepare to celebrate Steven's 14th birthday. However, Steven is feeling insecure about growing older and worried about how his powers might change. Despite his worries, the Gems throw him a birthday party, complete with games, cake, and presents.

As the party winds down, the Gems reveal that they have a surprise for Steven - a trip to the moon. They plan to visit the ancient Gem structures on the moon, hoping to find a way to stop the Cluster from forming. Steven is excited to go on the trip, but the journey proves to be more difficult than they anticipated. They have to navigate dangerous obstacles and avoid the watchful eye of the Diamond Authority.

When the Gems finally arrive on the moon, they are awed by the beauty and grandeur of the ancient Gem structures. However, they soon discover that the structures were built by Pink Diamond, who Steven has come to learn was actually his mother. As they explore the ruins, the Gems learn more about Pink Diamond's plans for Earth and the true purpose of the Cluster.

As they search for a way to stop the Cluster, Steven becomes increasingly homesick and worried about the future. He confides in Pearl, who reassures him that growing up is a natural part of life and that the Gems will always be there to support him. Steven feels grateful for his friends and family and vows to protect them at all costs.

The episode ends with the Gems returning to Earth, where they are greeted by Connie and Greg. Steven is happy to be back home and grateful for the love and support of his friends and family. He feels more confident about his powers and excited for what the future holds.