Strax

Commander Strax was a Sontaran commander who was demoted to nurse as punishment for an unspecified failure. He fought and died at the Battle of Demon's Run.

Biography
He was one of many people who owed the Doctor a debt. In the year 4037, he was tending to human soldiers at the Battle of Zaruthstra when he was summoned by the Doctor to help in the mission to rescue Amy and her baby at Demon's Run, which offered him a chance to once again experience the pleasure of battle. He was mortally wounded in the battle with the Headless monks when one damaged his probic vent. In his final moments, Strax noted how he had once longed to die in combat (which was common among Sontarans), and now, he didn't find it as enjoyable as he had thought it would be. Rory tried to comfort him, saying he was sure he would recover, but Strax wasn't fooled, reminding Rory that he was a nurse, too. However, he admitted that he had had a good life, and was pleased to live nearly twelve years. (DW: A Good Man Goes to War)

Personality
Strax generally displayed traits that were normal for a Sontaran, such as a willingness to die in battle and a love of fighting. Despite being demoted to nurse at some point in his life, Strax was still a fierce warrior who was willing to face overwhelming odds without hesitation or fear. An example of this trait was when he and several of the Doctor's allies were outnumbered by the Headless Monks yet fought valliantly against them. He also showed a willingness to kill people he had once helped; for example after healing a human boy he told him that he hoped to one day defeat him in mortal combat.

However Strax also had a softer side and appeared to like children tending to a young boy during the battle of Zaruthstra and offering to breastfeed Melody Pond, seeming rather affronted when Rory and Amy refused his offer. After becoming a nurse, he gene-spliced himself for all nursing duties. He told Rory that he could produce "magnificent quantities" of lactic fluid. Strax had vast medical knowledge, so much so that he would even give advice to his enemies during confrontations. As when the Doctor's forces surrounded Colonel Manton and his unnarmed Clerics, Strax told him not to slump as it was bad for his spine.

Despite the fact that most Sontarans considered the Doctor to be an enemy, Strax was a loyal ally to the Time Lord and did not appear to have any grudge against him. At the end of his life, Strax commented that he wasn't enjoying dying in battle as much as he'd hoped. However he was grateful for having lived nearly twelve years which, for a Sontaran, was quite a long life. When Rory tried to comfort him, insisting that he was a warrior and he could survive, Strax reminded him that he was a nurse.