Day of the damned - David Gunn

Lieutenant Sven Tveskoeg is a killing machine whose DNA marks him out as less - or perhaps more - than human.

He's survived everything a hostile universe can throw at him, but it's not luck that's kept him alive. A lucky man wouldn't be picked out of obscurity to serve in the army of his Emperor, OctoV, a machine-human hybrid who appears to be a teenage boy but is actually immeasurably older. Maybe Sven's survived out of sheer bloody-mindedness (although let's not forget his enhanced healing abilities and preternatural strength), but he's not one to dwell on such matters.

Sven and his squad of misfit auxiliaries are in Farlight, capital of the Octavian Empire, for a bit of rest and relaxation. But the emperor is missing and what begin as riots soon turn to slaughter as civil unrest becomes civil war. And behind the double-crosses and Byzantine betrayals that threaten to topple OctoV from the throne he has held for thousands of years is, of course, the U/Free, a galaxy-spanning empire with the technology of gods and the morals of school children. 

As anarchy takes over, Sven could choose to stay low and do nothing. But when has he ever done anything that sensible?