Monster Hunter Nemesis

Agent Franks works for the U.S. Monster Control Bureau, and he is assembled from other people's parts. He stands close to seven feet tall, is very hard to kill, and runs on a potent alchemical substance. A spirit older than humanity, and far more intelligent than any person, lives inside him.

One of the founding fathers made him swear to protect the United States from monsters. Franks agreed on a single condition. Whatever the government learns about his body or about the alchemy behind the elixir, it must never try to make more like him. If it does, the deal is void.

In a secret location, the director of his own agency is doing exactly that. Project Nemesis uses advanced technology and genetic engineering to produce thirteen new creatures modelled on Franks. The agreement is broken, and Franks turns on the people who betrayed him.

Baen published this in 2014 as book five of Larry Correia's Monster Hunter International series. Franks, not the MHI crew, stands at the centre, and flashbacks reach into his long history. Earl Harbinger, Julie Shackleford and Owen Pitt appear along the way.