They called him the 'Shinigami of Shiganshina'. Because that was where he was from, regardless of wherever he might choose to return to.
Because he'd fought off death so many times, there were starting to be whispers that death itself was afraid to claim him, who had emerged from one of the, as the populace had deemed to call them, 'Black Titans'.
He'd hardly say a word, to anyone, not even his own commanding officers, unless he had to. He'd simply stare ahead as though he wasn't even seeing anyone there, the only sign that they'd been acknowledged being a possible tilt of the head, a shake or nod.
And on the field, in battle… his movements were precise, effective, economic, and deadly. Titan after Titan killed, although many who were in his team - those who came for a while and pulled out, who saw what action in the Scouting Legion was like and had decided it wasn't for them - they said, that it was almost as though Kiryu didn't care if the Titans ate him.
They'd whisper that it was similar to others they'd heard of - that cadet, Eren, wasn't it? The one who only wanted to kill Titans. Except that this Kiryu didn't have anything else. Like that Mikasa, who was a skilled genius, but even she had something other than Titan-slaying.
Because of this, Kiryu was almost a wild card - he worked best on his own, but teamwork wasn't unfamiliar territory for him. Yet no one knew if one day his time would come, and death would decide, 'that's it, I'll take him today'. That one day, he'd simply not be there.
Except that then one night while they were at barracks, he was taken forcibly from his bed, and disappeared for several days. The rest of his squad asked questions, but the captain, who seemed to be the only one in the know, wouldn't give any answers.
Kiryu would reappear looking much like he'd been brought back from that dead state, but although he began talking to the others more, he wouldn't explain what had happened - apart from that 'a friend reminded him what 'satisfaction' was', which left them just as confused as before.
From then on, he'd occasionally vanish while they were inside the walls. He'd always be back in time, though, for meals, for lights out, for briefings.
He couldn't keep his new lease of life a secret forever, though, and soon they discovered him writing a letter - entitled to two people, 'Nico', and 'West'.
When asked, he said that he was helping to provide for them, ever since one of the Black Titans had eaten their father, some years after one of the 'normal' ones had done the same to their mother after the felling of the Wall Maria.
And then they'd remember who he was, and how he'd come to them, and they would look away, understanding now the reason behind the tears that stained his cheeks when he woke up, and the splotches of wet ink on the paper.
...
AN: Saying right here before anyone says anything about it - they Dark Signers/Earthbound called 'Black Titans' because... they're black. Seriously, go look at any Earthbound Immortal card, and that is what they look like in the AU.
