Troup is a fictional author who wrote Bad Twin before he actually boarded 815, the fated flight carrying our lostaways. Whether he is dead or alive, we're not entirely sure... Bets are on him being dead, though. I doubt the creators would seriously start to pick him up.
On Amazon, there's an exclusive interview with Troup (A fabricated interview, that is) where Alvar Hanso is mentioned and another book that Troup evidently wrote called the The Valenzetti Equation, which has something to do with a Princeton college professor and Hanso. Just as Troup is going to answer the question about how the book has mysteriously disappeared from shelves, the interview concludes... It's incredibly odd. The Lost creators have gotten Amazon in on the mystery!