A/N: A few thank yous to go around before the chapter. Thanks to my mom and dad for pointing out where I needed to improve. Also, thanks to Ryuujin (Whether you want to be thanked or not) for helping me outline the entire plot of this thing, as well as giving me Deathsong to use. Also, a small warning: From here on, the story gets really depressing. So if you want to be cheered up, don't read. (I feel like Lemony Snicket.) --- Chapter Four: Koukei (Replacement)

Zero transported into the base, wiping a slight trickle of blood away from the corner of his mouth. Today's mission had gone fairly well, although he still retained a nagging feeling that he wasn't doing as well as he used to, despite X's words the day before. Whatever the case, he was exhausted, and simply wanted to return to his room and relax for a while. He headed off down the halls of the large base, his red boots clicking against the metal floors.
However, the sight that greeted his eyes as he opened the door was not a relaxing one. Sitting in his chair was a tall Repliroid with long, silver hair. His armor was black and silver, and extended into long spikes at the elbows and knees, despite the sleekness of the rest of the design. His hair seemed to have been designed similarly, as it fell down his back in long, flowing waves, but at the bottom seemed to spike up sharply. In one hand he held a weapon that resembled in many ways a tuning fork, if said tuning fork had been extended a great deal and given pointed tines. He was leaning back, eyes closed, apparently deeply relaxed.
Zero was slightly annoyed at the intrusion, but decided to remain polite until he figured out what was going on. "Excuse me, but what are you doing in my room?"
The man opened his eyes slowly and turned to look at Zero. When he saw the blond Repliroid, he looked slightly surprised. "Oh, you mean no one told you?" he queried, raising one elegant eyebrow. Zero now had time to notice his eyes, which were as silver as his hair.
"Told me what, exactly?" asked Zero in a fairly annoyed tone of voice. He didn't want to play 20 Questions with the younger Repliroid, he just wanted to relax.
The man leaned back again. "Well, to put it bluntly, you've been replaced."
"What do you mean, Zero's been replaced?" demanded X in an angry tone of voice. Signas cringed slightly under his anger.
"Well, you see, X-san, we're uncertain about Zero's mental stability," the tall Hunter commander stated in a voice that was only slightly quavery. "First there was the breakdown yesterday, and today he performed incredibly badly in a mission. The mission was still successful, but he wasn't at all at his normal par. We believe he may have had a malfunction somewhere, and until we can correct it, we rather he stay here. It's only temporary, so don't worry."
"The entire reason he's been acting so unstable is he's worried about replacement!" raged X. "You'd know that if you actually TALKED to him for a little while!"
Signas sighed slightly. "X-san, we know that is most likely the reason for the instability, but we'd still like to run some scans on him before we give him back control over the Zero Unit."
X continued to look angry. "You better have replaced him with somebody who can actually fight for beans..." he muttered.
"No need to worry, X-san. Deathsong-san is a competent fighter. After all, he trained under Zero himself, so he can fight quite well," Signas assured him.
X sighed but nodded. "I guess this may be for the best... I've been worried for him too..." he admitted.
Signas smiled slightly. "Don't worry. Zero will be back in control as soon as we get those scans done."
Zero stared at the younger Hunter. "What do you mean, replaced...?" he said weakly.
The silver-haired man sighed and leaned back further. "You are no longer commander of the Zero Unit. I, Deathsong, am. What else do you need to know?"
"But... it's my personal unit! They created it for me! Why would they replace me?" Zero protested.
Deathsong shrugged. "I have no idea, personally. All I know is that they said, 'Here, Deathsong, take over this unit for a little while, your room is now down that hall over there, byebye!'"
Zero shook his head, his eyes staring at nothing. "This can't be happening..." he said, but the words sounded false even to himself.
"Sorry, but that's the way it goes, Zero-sama. I'm sure you'll have control soon, but until then, your room is down the hall and up that flight of steps."
Zero managed to get himself out into the hallway and to the steps before collapsing. Part of his mind was insisting that Deathsong was pulling a prank, that soon enough he'd come and give Zero back his room, his unit, his life. Part of his mind was just silent. And the last part was silent except for one simple statement...
I guess I was obsolete...