- Book one of "The Original Secrets" series - 'The secret lies here.' We all know Tatia Petrova, the 1st known doppelgänger of the Petrova family and the biggest weakness of the Original brothers, Klaus and Elijah. The story tells that the two brothers fell in love with her when they moved from England to the New World, where they became a love triangle. The last thing we know about Tatia is that Esther used her blood to make her children immortal. But we only know what the story tells, not what really happened. Because what really happened is a secret. A secret that could destroy the Original Family. A secret so big that the few people who know of its existence called it "The Original Sin".