Merida Island Base

Teletha Testarossa is a Whispered, born on December 24, 1981, the younger twin by seconds to her brother Leonard. Gifted in her own right, she is seen as a genius, her and her brother's intelligence worrying their parents. She is fluent in Italian, German, French, Latin, Japanese, Russian, and her native English. At a young age, she designed the full-cloak ECS that was then applied to a nuclear warhead sent to Kuwait, killing thousands of innocents. Since then, she carries the heavy burden of guilt and a strong sense of responsibility to protect innocents.

Her mother and father were killed in a raid on her house, only she and her brother spared when rescued by Borda, who then raised them. It wasn't too long later that Leonard left, and then they were approached to become founding members of Mithril. Tessa initially joined in the R&D Division, designing the TDD-1 and directing its construction around a retrieved hull of a Russian submarine.

She also worked alongside Bani Morauta, another Whispered who developed the ARX system and the AI known as Al. The two were mutually romantically attracted to one another, though it's unclear if either had ever made any move towards it becoming something more. After Bani killed himself, Tessa switched to the Tactical Division and took command of the Tuatha de Danaan.

Often seen as a well-bred, demure lady, she is viewed as a Goddess of sorts by the people under her comman. A tactical genius, she proves her mettle as Captain of the TDD-1 more than once, navigating through seemingly impossible situations and making calls that often worry others until the outcome is miles ahead of what they might have achieved themselves. She also shows herself to be quite ruthless in spite of her ideals, earning the last bit of unending loyalty of her subordinates after the fall of Mithril. By saying that their mission was one of revenge, to tear down those responsible for the loss of so many comrades, they all were willing to follow her to the end. The only ones who left were those with families or too injured after the battle, keeping nearly a full crew, one far larger than she expected.

Though she is charming enough for it to go unnoticed, she is somewhat awkward in social situations, especially amongst peers her age. A military brat, she moved around often when very young, and then became a member of Mithril, hardly ever interacting with others her age. She views Kaname as a romantic rival, though when Sousuke is not involved, the two are very good friends, and often work hard to protect one another. She acts as a mentor for Kaname in regards to being a Whispered, guiding her through some of the essential knowledge she would need not to fall prey to insanity.