He couldn't say why he'd signed on, but after he'd done it he felt safer, somehow; it felt right. Even with the acclimatisation, the new routines he'd had to learn, the stifling living conditions and (worst of all, in some ways) the crew, he felt that this is where he was supposed to be.

They'd had to let him go, of course; it fit the profile. Acid Warriors, conditioned to do that job, filled with hallucinogens and sent out to kill (he occasionally wondered if there were any other professions that benefited from chemical enhancement - Acid Sewerage Maintenance Workers?); when they got tired of it, it was only natural that they might want to get away from it all. Shards of personality emerging from the soft padding they'd been encased in would determine where each one went for that solitude they needed so badly.

It had to be a particular kind of solitude. Away from other humans, and most definitely away from the other Acid Warriors. The whole experience had been like getting too close to a friend, seeing them tumble towards your personal space like a mass transit vehicle out of control, unstoppable, Roche's limit of the psyche shattering both parties if they didn't manage to get some distance between them. But still, they needed company of some kind.

Some of them joined the fragment religions that attracted aliens, but most signed up with alien starship crews - the less humanoid the better. There were limits to how far they could go in that direction, of course; not every alien race would want a human around. There were enough who didn't care either way, enough to take them all in, one to each ship.

The race he'd found sanctuary with didn't have a name that could be rendered into human language; the closest anyone could get was a particular pattern of concentric rings scribed in graphite (it had to be done that way, the aliens insisted, otherwise it meant something entirely different), symbolising the magnetic fields they used to communicate. There were translators, but he knew that the exchange of ideas between them was marginal at best. There were several core concepts that he just didn't understand.

But they could make their wishes known to him at a very basic level. His duties on the ship were mopping, and replacing the heavy spherical batteries that powered their EVA suits. The ship was an asteroid mining tug, but he never got to see what went on outside; he'd only been allowed into the command space once, where the four aliens who shared the command of the ship examined him silently, reviewed his records and then turned away. An underling spent five minutes trying to get across to him the concept that he'd been accepted; the matter was complicated by the idea that their acceptance was only for a limited time and that they'd want to meet with him again at some point in the future. He'd been shown how to tell if a suit battery needed replacing, how to swap dead batteries for fully-charged ones - or at least half-charged; the aliens had the habit of running the batteries down until they were completely dead and then struggling back inside and making emotional pleas for him to change the batteries immediately. His ideas about fully recharging the batteries aroused a mixture of derision and tolerant good humour in the rest of the crew.

The mopping was the hardest part. Apart from the air (mostly methane; he had to wear a suit whenever he went outside his quarters and he thanked the goddess that the pressure was close to human normal), the sudden gusts of wind that the alien's air system made in imitation of their home world's atmosphere, the darkness (their primary visual sense was magnetic), the corridors themselves were madly uneven. Tube-like indentations ran down the sides, across the floor and up again; there were flanges set at random along the walls which bruised his arms. Even after two months he was still being taken aside by one crew member or another and told in a vaguely grandfather-to-little-boy way that there were some sections of the ship that he was not supposed to mop. These directives changed every week, to a pattern that he could not fathom. He made charts, diagrams and timetables, none of which helped. In the end he confessed that he had no idea where they wanted him to mop and, to his surprise, they stopped chiding him. From then on, he mopped the entire ship except for the command space, their living quarters, their altar spaces and the engine section.

It was wearying work. He was given a bowl-shaped container and shown where it could be filled with the cleaning agent - some extremely poisonous-to-humans chlorinated liquid. He found out how poisonous the hard way and spent a very nervous two shifts in one of the ship's altar spaces where one of the commanders silently prayed over him. They had little in the way of human medical care facilities, and he got better through luck and determination more than anything else.

He used a human mop; wooden handle, stringy brush bleached white by the chlorine fluid. The work itself was drudgery; dip the mop into the bowl, slosh it around on whatever even floor-surfaces he could find and leave it to dry. He didn't even know *why* they wanted parts of the floor mopped; it didn't perform any useful function that he could see. He supposed that it was a decorative or perhaps ritual thing.

His quarters were tiny, compared to the other spaces on the ship, but that reflected his status. For a while, he kept a light in there, mainly to read by and to help him locate his clothes. After three months, he found himself using it less and less, and after eight months he didn't use it at all. He located his things by touch, and he no longer read.

After a year and a half, the commanders asked to see him again. By that time he had come to know them better, even become familiar with their presence; floating in the command space while dozens of dark grey eight-legged horse shapes silently gestured at each other didn't inspire the same curiosity and sense of wonder it once had. After eighteen months he had partially merged with them. If he didn't understand them completely, he could at least emulate their slow, cautious way of moving through life.

The commanders examined him for almost three hours without communicating; then they turned away just as they had the first time they'd seen him. The gesture brought back an oddly displacing sense of the kind of person he'd been back then.

An underling - the same one who had spoken to him before, reinforcing the memory - told him quite simply: "We will begin to take you home soon."

It was only after he'd been returned to Earth and was hiding from the other humans in an ExPort suite that he realised: they'd pushed him away for the same reason he'd pushed the other Acid Warriors away. They had been getting too close.