I'm sure I found this on this site but can't for the life of me find the answer again.
I'm looking for a science fiction story that starts off on an alien spaceship. There is a human that was abducted and is now dealing with alien bureaucracy. While he is dealing with this another alien attacks the station.
The human manages to shrug off two blasts from a weapon that would kill other aliens and then proceeds to rip limbs off the attacker and kill it. This shocks the other aliens as it turns out that humans are far stronger than any of them.
I think it then moves to a point where the solar system is blockaded and the original bureaucrat tries to have this undone by working with the 'grays'.
The reason that humans are stronger is due to them evolving on a 'death world'.