Merida Island Base

A Whispered, Leonard Testarossa was born seconds earlier than his younger twin, Tessa, on December 24, 1981. A genius even greater than Tessa, their intelligence was a source of concern for their father, Carl. Exceptionally shy as a young child, he could not even be present in the house when company came over, staying with family friend Borda. He is fluent in Italian, German, French, Latin, Japanese, Russian, and his native English. It is uncertain if he learned any other languages after separating from Tessa.

When a young child, he caught his mother in bed with another man while his father was deployed. A few months later, their home was invaded, and Maria hid Tessa away while begging the intruders to take Leonard and spare her. They killed her anyways, and the two kids would have been kidnapped if Borda had not arrived after being contacted by Carl and saved them.

Leonard did not stay under his custody for long, running away to join Amalgam. While there, he developed the Codarl, Alastor, Behemoth, Eligor, and Belial, his Whispered specialty clearly in AS design. Using their resources and the ability to glean bits of the future through the TAROS system, Leonard began dismantling the web of power that made up Amalgam, rising to the top and eliminating anyone in his way.

He is a sociopath with little regard for others. Viewing himself as greater than all, he plays himself as a charmer, but in reality, he's actually quite vulgar. He thinks of most women as little more than sex objects, easily convincing many of the women under his command to his bed. Though he never fully forced himself on Kaname, he did kiss her without her permission more than once, even when knowing she had nothing but scorn and disgust for him. Part of his nice boy act included using the Japanese word 「僕」(boku) to refer to himself, the word casual in voice, but not rude. Later, when he drops the mask and begins abusing Kaname, he adopts the word 「俺」(ore) which is very vulgar in nature.

He thinks nothing of all the deaths he leaves in his wake, claiming that they will all be made right when the TARTAROS is activated and the world is recreated to a peaceful ideal. He never even once considers the ramifications of his possible failure, believing himself infallible. He even has no regard for those under his command, never showing any remorse at their fates, even when knowing they will be going to their deaths.

He is capable of charming even enemies, bringing Kalinin over to his side and even swaying Sousuke into a state of confusion over right and wrong. In the end, though, after his failure, he wishes simply to bury it, and Kalinin kills him before he can hit a self-destruct button.