Get a 30 Day Crunchyroll free trial here: http://www.dorkly.com/crunc... Steven Universe killed his mother, just by being born. That's...pretty heavy for a cartoon.
Garnet, Pearl, Amethyst and Steven have covered some pretty mature topics across multiple seasons of Steven Universe. And in some episodes, Greg Universe, Lapis Lazuli, Peridot, and Connie have brought up other mature themes! From gem fusions being sex, to the implications of Steven and Connie's fusion of Stevonnie, Rebecca Sugar's show does a lot of interesting things!