Steven Universe: The Movie

Spinel wants to destroy Earth because she was abandoned by Pink Diamond (Steven's mother) 6,000 years ago. Pink Diamond left Spinel alone in a garden with a rejuvenator that reset her memory, only to never return. When Spinel discovers that Pink Diamond became Rose Quartz and then Steven, she becomes consumed with vengeance and decides to destroy the planet that Pink chose over her.

Pink Diamond left Spinel in a garden with an injector that she claimed was a game - stand still and don't move for as long as she was gone. When Pink never returned, Spinel stood there for 6,000 years until she was finally freed by the Diamonds, only to learn the painful truth about her abandonment.

Steven doesn't defeat Spinel through combat. Instead, he absorbs her poison injector into his own body, demonstrating that he's willing to share her pain. This act of vulnerability and empathy breaks through Spinel's anger, and he offers to help her find a new purpose and family.

Pink Diamond left Spinel behind because she was escaping her responsibilities as a Diamond to become Rose Quartz and live on Earth. The explanation in the movie suggests Pink either forgot about Spinel or chose not to return, though Steven speculates she may have thought Spinel would be happier not remembering her.

Spinel's injector is a weapon that releases a pink poison substance. The poison travels through the body and can rejuvenate gems, effectively erasing their memories and powers. Spinel uses it to attack Beach City and later injects Steven directly, forcing him to experience the pain of memory loss.

Steven learns that love isn't just about happy moments and perfection - it's about being there for people even when they're at their worst. By accepting Spinel's pain and choosing to help her rather than defeat her, Steven demonstrates that true love means accepting people despite their flaws and helping them heal.

The movie takes place two years after Steven and the Gems established peace across the galaxy. Steven has been living a normal life on Earth with his friends and is now facing a threat directly tied to his mother's past. This is the first major challenge in this new era of peace.

Spinel changes sides because Steven's act of absorbing her poison shows her genuine compassion. She realizes Steven isn't Pink Diamond - he's a separate person who chose to help her rather than fight her. This kindness gives Spinel hope that she can find a new purpose and family.