If Klaus was asked to single out one superficial thing he loathed about being in shackles, he would say it was the collar. It was always cold, like the metal was designed to block heat rather than conduct it. It pinched at his throat whenever he swallowed or turned his head, that brief sting reminding him that his life belonged to someone else. It could blow his head clean off at the touch of a button if he dared to step foot outside the barriers set for him, guaranteeing his obedience and his isolation from the world outside. But one of the worst things about the collar permanently clamped around his neck was that it was just slightly too small; he couldn't breathe properly if he wasn't facing straight ahead, and the compression to his windpipe had caused a patch of bruising to peak out from under the metal. With no relief, coupled with the Legion's mentality that medicine makes one weak, he'd probably have that splotch of dark purple and faded green until the day he died.
There were other things Klaus hated, of course. It came with the territory. Once one got passed the notion that he was a living, breathing, thinking, sentient being who was viewed as property to be mistreated at the whim of the owner, there was still the malnourishment, the scraps tossed at him by Legionnaires indoctrinated into a totalitarian rule from the moment they were born. There were still the problems with his head: the chunks of static that clung to his subconscious as the shadows of memories not quite clear enough to decipher; the headaches that were getting steadily worse as his unknown condition went untreated, and that nasty, jagged scar that struck out from under his hairline as the last clue towards a major, life-changing injury that he couldn't even remember.
But the emotions were there, every time he caught his murky reflection in the river by the Fort, or felt that sudden aching jab when one of his headaches started. A vengeful anger that only a victim can feel, but not directed towards Caesar, or the Frumentarii, or Legate Lanius. It was misplaced, yet somehow felt accomplished, as though he had already settled the score. Whenever he tried to grasp at the memory, he could only hear random sentences from the same voice: "you've made your last delivery, kid." in a smooth, business-like tone, and "you sick, vindictive fuck!" spat at him in a mixture of hopeless fear and rage barely held back. It was those fragmented audio clips that only reminded him that his past was gone, all the bullshit that the Legion had fed him about growing up here was false, and he'd probably never live to find out what was behind those locked doors covered in cobwebs and caked in dust.
Sometimes he wanted to step a few feet too far, get his head blown up in a flurry of blood and chunks of skull, go out with a quite literal bang. But whether he liked it or not, this was his life, and he was too much of a coward to dare to end it prematurely.