Unmarked spoilers are ahead, per Spoilers Off rule.
Jonathan's refusal to be the Continental's sex slave even as he's being brutally beaten up as well as raped by him. (His "no, no, sir" doesn't come from him wanting Continental to stop, but about refusing his offers).
During a sparring session, the Continental decides to make an example of Jonathan and beats him unconscious in front of the soldiers. Unable to stand back any longer, Leonard steps forward and demands to fight the Continental in Jonathan’s place. Angry at the interruption the Continental lunges at Leonard, who knocks him flat with a single punch.
When Leonard rescues Jonathan while he is being raped by Continental he immediately draws his knife. Continental—who up to this point had been a sexually violent authoritarian—can only sputter in disbelief and cowardice, feebly admonishing Leonard for drawing a weapon on a superior officer. Leonard only responds that he will never respect Continental and then promptly castrates him in retaliation for what he did to Jonathan.
Jonathan’s character arc is tragic but also awesome. He overcomes a hellish boot camp where he is sexually exploited and then raped and losing the man he loves, and goes on to command his own unit on the battlefield. And though he faces further tragedy when he finds Leonard assimilated with an Apocalypse alien he ultimately keeps his promise to Leonard and kills him to save him from his fate. Jonathan’s perseverance in the battle is documented to be the first victory for humanity against the Apocalypse aliens. Who knows where his character arc would have further gone had the OVA not been cancelled.
