Cosmo is fundamentally kind-hearted but carries a lot of emotional weight. She's plagued by guilt over being unable to save anyone from her home planet, and this feeds into a persistent self-esteem problem—she frequently calls herself "unworthy" or blames herself for the hardships her friends go through. While she dislikes violence and prefers peace, she's realistic enough to acknowledge that sometimes fighting is unavoidable, even if she personally can't participate in combat. She's prone to clumsiness but makes up for it with resourcefulness, though she also has a knack for accidentally getting into trouble. Fans often note her similarities to Maria Robotnik and Tikal—all three are pacifists who've made serious sacrifices, yet all understand that fighting can become necessary.
Cosmo's backstory is tragic. Her original home world was already destroyed by the Metarex before she was even born, so she grew up on a space colony instead. That peaceful life was short-lived; the Metarex attacked her new home too, killing her family including her mother, Hertia. During her escape, the Metarex planted a tracking device on her, and worse, they installed a surveillance device in her brain that let them see and hear everything she experienced.
She eventually crash-landed on Sonic's world, where Tails, Cream, and Amy discovered her. Cosmo was searching for "the legendary hero that can use the Chaos Emeralds"—Sonic—but stayed cagey about her reasons until she spotted him from Tails's ship and rushed out to plead for his help.
Sonic agreed. This kicked off a massive adventure across the universe aboard Tails's new spacecraft, the Blue Typhoon, with Sonic, Cosmo, Tails, Knuckles, Amy, Cream, Cheese, and Chris Thorndyke all on board, hunting down the Chaos Emeralds that Sonic had scattered during his first confrontation with Dark Oak.
Content compiled by AnimeList.moe from publicly available sources.
