Rem departed Earth aboard Project Seeds when the planet’s resources were entirely depleted, rendering it uninhabitable for human life. In their quest for a new home, the remnants of humanity, carrying cryogenically frozen humans, traversed the stars until they discovered a young Vash and Knives alone on a hostile planet. While most of the crew wished to eliminate them, Rem intervened and saved their lives. She treated Vash and Knives as human beings rather than monsters, unlike the majority of the crew.
Rem's favorite place on Seeds was the holographic Eden, a smaller simulation of her old home on Earth, devoid of war, theft, or hate. Vash became deeply attached to Rem and adopted her life philosophy. His brother, Knives, also loved her but interpreted her teachings differently, which some view as nearly refuting them altogether.
Rem is Vash's inspiration. She's the reason he refuses to kill because she once said, "No one has the right to take the life of another." She is also the inspiration behind Vash's choice to wear a red coat. Rem's favorite flower was the red geranium, symbolizing unwavering determination. Wearing the red coat not only reminds him of Rem but also serves as a reminder of his vow not to kill and to help others.
(Source: Absolute Anime)
