The Hero (novel)

The Hero is a novel by John Ringo and Michael Z. Williamson, and is part of the Legacy of the Aldenata series. It is set in the future after the defeat of the Posleen, and features a Darhel named Tirdal who is the first of his race to be assigned to a military team. The Darhel have a genetically programmed limitation - they cannot kill, or they descend into "lintatai," a type of madness followed by catatonia and death. When things go wrong on a mission, Tirdal must somehow overcome this disadvantage, or lose his life, and possibly the future of his people.