Of all the characters in Steven Universe, none has the reputation that the elusive Rose Quartz possesses. Six thousand years ago, Rose landed on Earth alongside her leader Pink Diamond when the latter gained dominance over the planet. Earth was originally intended to be used as a resource ground for numerous Kindergartens, destroying the inhabitats in the process in order to create new Gems. Having fallen in love with Earth, Rose rebelled and created the Crystal Gems to fight back. The war ended in the Crystal Gem's favor, but not without severe consequences, lest of all Rose and her comrades stuck on Earth with no home to go back to. Rose seem to have taken it all in stride; the diversity and ever-changing structure of Earth always fascinated her and she took to her self-imposed exile beautifully.
Eventually Rose met Greg Universe whom she shared a romantic relationship with. Their bond would create Steven, their son, but at a huge cost: Rose's life. Sort of. Rose gave up her physical form so Steven would be "half" of her, inheriting her Gem and powers. Given the Gems' biological structure, to what extent she meant by that is unknown. Either way, her missing presence is constantly felt by her fellow Crystal Gems and for better or worse, her son Steven.
Much of her life and her personality is a looming mystery that Steven spends the show slowly unraveling. Both his father and the Crystal Gems speak of her with great revere. Rose Quartz was kind; Rose Quartz was compassionate; Rose Quartz loved every living thing in the world. In Steven's eyes, he saw a hero who protected the Earth from "evil." Following under his mother's shadow, Steven tries his best to live up to her legacy, attempting to emulate her empathy and skills in spite of overwhelming pressures.
As Steven learns more about his mother, he'll start to see the crack behind her supposed perfection. Rose Quartz, the Gem who loved everyone and cared so deeply for everything, may in fact, have done questionable things that contradicts who this Gem supposedly is. Most surprising of all is that Rose may have kept secrets from her own companions! Rose's past is an endless series of contradictions and while there is no doubt she is as kindhearted as the others say, even she has skeletons in her closet. Steven must slowly understand that he doesn't have to be his mother, but his own person.