She liked to play.

  That was the bottom line, and as far as Salma was concerned play could only be good for her – and, luckily, Captain Hild agreed, as did quasi-doctor Meriel. So the crew was mandated to play too, and play nice.

  It had been immediately evident that Feathers was an intelligent, emotionally complex being. You could see that in the constructive nature of her play, and in her evident attempts to communicate in her very avian chirps and trills – sometimes long symphonies of such sounds – which the Shadow’s computer banks were doing their best to interpret, without success so far.

  And her intelligence showed too in ways no machine could have detected. Especially in the way she responded to Salma, as she had from the moment she opened her very bird-like eyes. She soaked up empathy, and tried to return it too – by bringing Salma bits of food, for instance.

  Even so, in the beginning she had been very quiet, still – shy perhaps, although Meriel had counselled against reading too much into the body language of such an alien creature. And sometimes she retreated into herself. She would be content to be with Salma for long hours – and only Salma – especially after sleeping. Or sometimes she would just sit, while Salma got on with other things – personal stuff, like sorting out her clothes, or changing round the furniture in her space in their improvised surface habs, even productive work. And when Salma slept, Feathers would crawl into a corner of Salma’s toom, sometimes sleeping herself, sometimes simply quietly waiting. This never troubled Salma.

  At other times, though, Feathers would sit quietly with Meriel. She seemed to have a bond with the healer who had patiently worked out how to feed her and fix her minor injuries. Meriel said that she was second favourite and was happy with that.

  Or Feathers would just wander around, usually with Salma at her side, watching the business of the other humans with her wide, black, enigmatic eyes.

  The rest of the six-strong crew mostly tolerated this behaviour, though Salma thought that Boyd, the oldest and most stuck in his ways, found Feathers’ watchfulness a little creepy – especially as he couldn’t read her expressions. He would say, ‘What is she thinking?’

  At the other extreme of engagement, Feathers liked to run races around the habitat with the youngsters, Salma, Zaimu – races which, super-fast on those skinny, very reptilian legs, she always won.

  After the first couple of years the small hab dome they’d set up to live in, adapted from an inflatable module for use during the spaceflight, had clearly become much too small for her. Feathers just couldn’t run far enough away, find remote enough locations for her stashes.

  Well, Feathers had become the mission’s priority, along with the ongoing monitoring of Planet Nine. And so, guided by lightspeed-delayed advice from specialist teams at the various Conserver stations, the crew had quickly constructed a much wider habitat around the old structure’s core technological suite, with its life-support systems. Improvised from more cannibalised components from the Shadow, the new hab evolved into a spacious multiple tent, essentially, but with inner panels and closed-off sections, so there were plenty of places for Feathers to explore and hide – and fall back shelters in case of leakage.

  The development inspired some grumbling from some of the crew, especially old Boyd, and especially since chunks of their solar sail had been used, or misused, in the construction. But that didn’t matter any more; the Shadow was never going to leave Nine, Hild would say patiently. The Cronus would soon be on its way, and eventually they would all be taken home in style, Conserver conscience or not.

  And in the meantime Feathers had evidently loved it all, using the new spaces to wander, explore – and hide still more stuff.

  But by now, four years after her retrieval from the mysterious interior of Nine, Feathers was changing. Her behaviour now was often more like an older child, or a young adult – ‘that kind of awkward transition age’, as Meriel tentatively put it – and the games she wanted to play had become ever more elaborate, her runs and explorations more energetic, faster, longer, although she was never far from Salma for very long.

  And, at some point, she had started to take stuff away with her.

  Nobody noticed this at first. Eventually Salma and Meriel found what she was doing.

  She was building evidently meaningful piles from discards – mostly old clothes and tools and empty food packs – sometimes out in the open, sometimes hidden in corners of the habitat. These trophies were carefully selected, but were generally just recycler-heap junk to the crew, a distinction she learned quickly once Hild had carefully instructed Salma to show Feathers what was vital and what wasn’t. Salma kept an eye out even so, just in case something important did get lost in the kipple heaps.

  All these behaviours seemed natural, as far as Meriel could tell, so she said, given this was the only member of her species humankind had ever encountered.

  Feathers was evidently growing into a healthy, fast-moving, roaming, exploring creature, putting her own stamp on the place in her own way. But she did change with time, it seemed to Salma.

  Mostly, Feathers started to become a little more solitary.

  More often now she would build her heaps of stuff alone, even more well hidden in some corner of the habitat. They were more orderly too, often circular in form, or arcs of circles. Sometimes she would show the results to Salma or Meriel, sometimes not, though she was not yet hostile to Salma coming to see what she was doing, or to accidental discoveries by the rest of the crew.

  One day in that fourth year – a day when she had hardly seen Feathers at all – Salma talked this over, not for the first time, with Meriel.

  And Meriel just shrugged, as usual. ‘All we can do for now is keep an eye on her, and let her develop at her own pace, her own direction. As we’ve done from the start. Just keep her safe; stop her from getting frustrated, if you can. We don’t know enough about her physical needs to be able to intervene safely, let alone her psychological needs …

  ‘Why, if you think about it, we don’t even know how old she is. Either in absolute time or relative to humans – or even relative to birds and bird-like creatures on Earth, which is what she most resembles. She has grown in the four years since we found her – I can measure that, at least, and I do every ship’s day – but that growth rate is slowing, it seems to me. So she might be like a human adolescent. Topping out. Or not. We have to be wary—’

  ‘Of making simplistic parallels,’ Salma trotted out. ‘Concerning a being from an entirely different biosphere.’ She held up a finger and spoke pompously. ‘Indeed, from an entirely different evolutionary trajectory.’

  Meriel grinned, self-deprecating. ‘I do not speak like that. Well, at least it’s sinking in.’

  This time Salma did have a new question. ‘You’ve measured her growth rate. Can you, umm, project that back? Can you guess how old she is, at least?’

  Meriel pursed her lips. ‘Good question. Answer is, yes, we can guess. But you have to be aware it is just a guess. We have four years of observational data, and absolutely nothing on her development before, and no comparison specimens to learn from. I know you don’t like me using the word “specimen”. I can tell you her overall growth rate must be faster than a human’s. Maybe twice as fast. But, given she hasn’t grown twice as tall since we found her, or doubled her mass, most of her growing must have been done before we encountered her. I think I’d tentatively put her down as equivalent to a human eighteen-year-old. Just coming out of an adolescent growth spurt. But in calendar years I’d say she is no more than nine, ten.’

  ‘Does that mean she’s living twice as fast as we are? I mean—’

  ‘Don’t go jumping to conclusions,’ Meriel said cautiously. ‘If I was a real doctor, let alone a real biologist, I probably wouldn’t speculate away like this at all. But … we know that her anatomy is more like a bird’s than a human’s. Her physiology is fast, high-energy, compared to ours. But birds can live for many years in the wild, back on Earth. Albatrosses, ostriches, big birds like that, may live three or four decades.’

  ‘Humans live twice that long, if they get the chance.’

  ‘Yeah, but remember that birds do use up a lot of energy in flight, and there’s a lot of wear and tear on the muscles and so forth … I know even less about birds than I do about humans. And still less about Feathers, who is some kind of bird-analogue from someplace else, not really a bird at all.’

  Salma tried to think that through. ‘But if she’s growing old twice as fast as I am,’ she said slowly, ‘maybe she was younger than me when we found her. Now she’s effectively older …’

  ‘Don’t think too hard about it. We don’t know; we only have this one specimen, who only just seems to have grown to adulthood herself, or near it.’ She reached over and touched Salma’s shoulder. ‘Don’t fret it. Just keep on doing what you’re doing, which has been the right thing from day one. Just be with her. Make the most of the moment …’

  Because Earth is on the way. Because this moment may not last for long.

  They sat thinking that over a while, in silence.

  Salma knew that the rest of the crew – the more thoughtful of them at least – spent a lot of time thinking hard about Feathers too, and the mystery of her weird origin. They could hardly fail to do so, given they had been living out here on the edge of the Solar System, four light-days from home, with ‘possibly the most baffling conundrum since the dawn of the scientific age’, as adviser Vasta had once put it. ‘And it’s got us trapped out here,’ as Boyd had added.

  That remark about a trap was valid, inasmuch as they had been pretty much mandated to stay on the spot and observe the various conundrums of Planet Nine until the much better equipped and staffed Cronus showed up.

  But now the crew all seemed to have mixed feelings about that too. Nine was their prize, won after decades of travel. These were their discoveries. Salma herself felt dismay at the thought of ‘some vast gaudy liner turning up with a cargo of celebrity scientists’, as Boyd put it. While she wanted to understand more about what was going on here, she also didn’t much like the idea of a circus like that arriving at what had come to feel like home, for all its remoteness, all its strangeness.

  Her home. And Feathers’. What would become of her when the Cronus arrived?

  A soft bleep; she checked her wrist. ‘Hey, lunch time for Feathers.’

  Meriel glanced around. ‘And she’s out of sight. As usual these days.’ She stood, stiffly. ‘You want to send out a drone?’

  ‘She doesn’t like drones. I’ll go find her.’

  ‘And I’ll help you search. You go clockwise …’

  It turned out that Meriel found Feathers first this time, and brought her back to the heart of the hab, where the rest of the crew were gathering for their own lunch.

  Captain Hild had always insisted that everybody show up, unless unavoidably detained, at meal times each working day. They had been effectively grounded for years and a strict ship’s schedule wasn’t necessary, but still Hild kept to a regular timetable, and she used meal times in particular as three opportunities a day for them all to gather. Good for the morale and team spirit of a good-natured but cynical crew, as Hild had quietly described it to Salma.

  And from the beginning here on Nine, at Zaimu’s suggestion, Feathers had joined the group for their midday meals.

  Today Meriel and Feathers were the last to show up, a little later than Salma. Salma sat on a chair improvised from a packing case, at the hub’s low table, scavenged from the ship.

  Feathers settled willingly enough – on the floor. As usual she eschewed the crew’s chairs, though one was always brought out for her as a courtesy, as Salma had insisted from the earliest days of this strange arrangement, so Feathers wouldn’t be left out.

  The crew’s food was briskly set out on the table, by Boyd and Joe today, their turn. It was the usual high-protein, low-fat meat and cheese substitutes from the recycling system, with authentic green vegetables laboriously grown in the hydroponics bays by Meriel – when she had time for her day job, as the supposedly part-time doctor insisted.

  Meriel and Salma tucked in hungrily, having put in some exercise tracking down Feathers in the depths of the habitat. Joe the comms guy, sweating, had evidently been working out, probably as per the rota Hild had set up as soon as they had settled here for what was evidently going to be a long duration. Boyd filled his face, as he put it, in the way he always did, as Salma had long observed. Zaimu ate more slowly, picking at his food, as he always did.

  The six of them. And Feathers.

  She sat on the floor with her long, scaly legs up against her chest. And as usual, before she turned to her own food, she explored some of the human supplies, feeling stuff, taking it apart, even chewing a little of it.

  Salma and Meriel had talked this over from the start. Evidently Feathers was an intensely social creature, even if in this setting the other social creatures around her were so strange, their food so unpalatable. Salma and Meriel had persuaded the rest to keep up this gentle imitation of the kind of feeding group Feathers seemed to need, instinctively, wordlessly. They had been supportive – welcoming to a stranger. Meriel assured everybody that she made sure the human food Feathers sampled would be no more than roughage for her, with little or no useful nutrient content, harmless. Water to drink was fine … They all took care not to eat the fragments Feathers had handled, though.

  Her own food, researched and synthesised by Meriel, looked like seed, or like animal flesh, or some kind of pulpy vegetable, much of it softened with water – and the water was the only authentic, non-manufactured Earth like ingredient. Feathers would nibble and suck at this stuff, her beak working quickly, her head ducking down to take a mouthful of food and then rising up as she swallowed, all the time gazing at the crew as if they intended to steal it. She never seemed more bird-like than when she ate, people said – people who had seen birds for real.

  To get this far, Meriel had thoroughly analysed Feathers’ organic chemistry. She had her own distinct suite of amino acids and proteins, different from any human, indeed any terrestrial bird – and Meriel had synthesised a range of food products on that basis. There had been a period of experimentation with what Meriel called her chemistry set, tweaking flavours and textures and above all nutrient value. The final food package was essentially based on a kind of reverse-engineering of Feathers’ own digestive system, and her waste. Meriel had tried to replicate what she thought that digestive system was designed to process as input, given her output waste as a clue.

  It seemed to work. Feathers cautiously tried out each resulting foodstuff, accepting or rejecting. But her tastes seemed to vary; sometimes she would reject what Meriel had presented to her before.

  But as she had grown the cuisine had had to evolve. Sometimes Feathers’ weight had dipped alarmingly for long periods, before beginning to recover as Meriel got her act together once again.

  Even so, to be able to nurture such an alien creature at all, from scratch, seemed miraculous to Salma.

  Meriel was modest about it. She said that Conserver life-support systems and their recycling capabilities were already the most advanced of any human society’s, even Earth’s. The systems depended on a principle called ‘molecular sustainability’, she told Salma. In a closed life-support system, by now a centuries-old spaceflight technology, human waste products – exhaled breath, liquid and solid wastes – were broken down at the molecular level into nutrients for crops and edible organisms such as yeast, along with oxygen and water extracted from the air.

  So, once Feathers was eating regularly and producing waste regularly, a similar closed-loop recycling regime could be set up for Feathers’ benefit, with her own waste passing through a series of scratch-built bioreactors: mechanical, adapted from human analogues, impressive novel creations designed to mirror the biological systems and processes Meriel had defined in Feathers’ own body.

  All these experiments and achievements were based on principles and technologies that had been given freely by the Conservers to the crowded nations of Earth, to help sustain what was still, after all these decades since the twenty-first-century crashes, a hungry planet. Now all this careful understanding was being adapted to support an isolated alien. For Feathers, these laborious experiments had evidently worked – eventually. And Salma, young and naive as she knew she was, had been amazed as she had come to understand to learn what the feat of feeding Feathers actually amounted to: Meriel was essentially synthesising the products of an entirely alien and unknown biosphere.

  But the food produced for Feathers certainly did not look, smell or taste like human food. It was off-putting if you sat too close while you ate.

  And, as the crew queasily discovered – though she did defecate in pretty much the same way as a human – Feathers did not eat as a human did. She used her wings.

  Salma had discovered, by looking stuff up when she had needed to, that on Earth birds’ wings were a kind of degeneration, or remodelling, of the hands of four-footed land animals. One long, heavily evolved finger had become the spine of a wing. Feathers had something like that; she was like a flightless bird – though in her case the wing-hands were evolving back into hands.

  So when she reached for her food, Feathers would fold her wings down over the plate, and the hand-like aspect took over, scraping at her plate with long, bony fingers evident beneath a sheen of feathers.

  Even that wasn’t so odd for observers, compared to when she kicked off the boots Hild insisted she wore, to reveal feet with claws. The boots were intended to save damage to the habitat fabric, rather than to Feathers’ feet.

  And with the foot-claws she would just grab food and lift it to her mouth. All this with a smooth, continuing rustle of feathers, over her wings, her back, her chest. But at meal times, this could be pretty distracting.

  Salma found that if you thought of her as a bird when exhibiting bird-like behaviours, and human when showing human-like behaviours, it didn’t put you off so much. Mostly that worked OK. But eating with her was always a challenge.