Sergei Orlov is a descendant of Daniel Orlov. David and Lia meet Sergei while on their honeymoon in Saint Petersburg, Russia after David tracks down Orlov descendants. The three of them immediately become intimate friends.

Sergei is a survivor. His family was one of the most powerful families in Russia before the Revolution. He grew up in Paris and lived between France and New York before returning to St. Petersburg in 2003.

Sergei has tremendous willpower. He is a recovered alcoholic and quit a three pack a day cigarette habit. He is a man seeking moderation and tranquility in his life, and is now content to be alone.

Sergei is a gifted jazz saxophonist who plays in a band named the Stray Dogs. In Volume Three, "Living Timekeepers", his career goes through the stratosphere after being featured in Oblivion's "Only This Moment".

Sergei remains a dear friend of David and Lia, and develops a deep friendship which turns into romance with David's mother, Theresa.