Steven Universe is a boy living in the fictional town of Beach City with Garnet, Amethyst, and Pearl, three female alien magical beings known collectively as the Crystal Gems. Crystal Gems protect the Earth and were established by Rose Quartz, Steven’s mother. After Rose needed to give up her physical form to give birth to Steven, Garnet, Amethyst, and Pearl took on the responsibility of raising him. Steven’s dad, Greg Universe, is a Human who lives in a van and works at a car wash. Steven maintains a good relationship with him and visits him regularly.
Steven has Rose Quartz’s gem and throughout the series it’s revealed to him exactly what that means and the responsibility it brings. The Gems help train him to use his powers as he grows older.
The amazing thing about this show is even though it’s about a male character and the story is told from his perspective, 90% of the show characters are female and mostly voiced by People of Color. Showrunner and creator (and out bisexual), Rebecca Sugar is the first woman to have a show on the Cartoon Network and she is the best answer to the Network’s male-centric programming.
The show takes on topics like alternative families (Steven essentially has 3 moms), queer relationships, defying gender norms, leaving abusive relationships and many other themes not usually covered on kids TV. Soon it comes to light that Pearl was in a long-term, open, love relationship with Rose and Rose left her for Steven’s dad. Garnet is a fusion of 2 gems: Ruby and Sapphire. Ruby and Sapphire fell in love and chose to remain fused as Garnet forever.