Intelligence. Language. Greater height, dexterity, and problem-solving skills. Altered eye color. The ALZ granted these gifts to apes, but took one away: fertility.

In the ape colony tucked away in the forest once known as Muir Woods, the youngest in the colony was six. His mother, one of the last fertile females, had died in a complicated childbirth. There had not been a single baby born since, and only a handful of miscarriages.

In desperation a tentative, last-ditch suggestion was made at the council: interbreeding with humans.

The reaction could only be described as mixed. There were outraged screeches and thoughtful hoots, shrugs of acceptance and brows twisted in skepticism. Talk ranged from the taking of captives, or finding a human settlement (if any still existed) and forming some kind of agreement. Hands flashed in a flurry of signs: what if humans were infertile, too? What if they'd all died out? Surely a pregnancy would not succeed?

The council ran long into the night, and by the time it finally disbanded, the first wash of sunrise glowed pink on the horizon.

Your tongue was as dry as sandpaper, your temple sticky with what you sensed was blood, and your memories no more than hazy snippets. You'd been walking on your regular route to the river for water, the rocky bank slick and icy from the night's freeze; you remembered your feet slipping out from under you and the crack of pain lancing through your skull.

There had been flashes of unfamiliar faces, the uneven sway of being carried, a cacophony of strange hoots and calls closing in around you. Now as you pulled yourself from the fog you were aware of the charred scent of a fire, and a mat of something soft beneath you.

Somehow, before you even cracked open your eyes, you knew you were being observed.

You were in a large, low cave, and a small distance from you sat two apes. You hadn't seen apes in years but with a lurch of fear you recognized the russet fur of an orangutan and the dark, distinctive silhouette of an extremely large chimpanzee.

To your disbelief they appeared to be actually communicating via sign language. Impossible; a hallucination from the blow to the head. Through your lashes you watched with stunned fascination, tracking their big hands: the easy fluidity of the movements, the changes in facial expression, a shrug here or a scowl there, punctuated by low sounds in their throats.

You'd heard rumors, of course; monkeys in the woods. Clever ones. The virus that killed people, some claimed, in turn made apes smart. So many had been slaughtered by panicked people during the Flu, but it wasn't unreasonable to assume some could have fled into the wilderness. And while gossip is just that, there were enough stories to convince you there had to be some truth to it.

But this was no diseased band of escaped animals.

They knew you were awake, you realized, as heads swiveled in your direction. Your heart skittered in your chest. You said nothing, but it was pointless to feign sleep. You raised your head and your vision swam; you breathed long and slow, willing the nausea to pass. It trickled away, and you tucked your legs under you and cautiously sat up.

The chimpanzee mirrored you, rising upright and drawing closer. Shoulders squared, he looked hard at you down his flat nose.

He possessed not just the strong brow typical of his species but especially heavy-lidded eyes, intense and startling in color: a crystalline golden-green. His mouth was stern as he assessed you and his gaze was sharp, missing nothing. An animal power imbued him but it was not mere animal intelligence observing you. The more of him was in his carriage, his countenance, the self-possessed grace of his movements.

This ape was smart, self-aware, and all but human.

"Alone?" The word rumbled out of him.

You could only stare. His voice was deep and rough, as if rusty with disuse, but he'd... spoken.

"Yes," you whispered back. "I'm alone."

Perhaps you should've lied. Told him you had friends in the woods who would be looking for you. Friends with weapons.

Too late now.

"Apes... found you," he informed you, and even with his stilted cadence, his tone was brusque. "Hurt."

"Thank you," you offered hoarsely. He gave no response to that as he turned, tossing a few signs the orangutan's way. Whether it was the injury or the shock of talking primates – or a cumulative effect – you felt lightheaded again and went down on your elbow, squeezing your eyes shut until you saw stars.

When you reopened them the ape had vanished. In his place was the orangutan, looming over you with a look you could only interpret as... kind. With one long-fingered hand he gave your arm a single, soothing pat, and his intention was clear – stay. Rest. As you sank back down you slipped smoothly back into the mantle of sleep.

You did not wake until the next morning. Breakfast was brought – berries and some kind of cooked root – along with a pungent paste of herbs for your head wound. This was administered by a small chimpanzee, face adorned with a feathered veil that, in what you were sure was no coincidence, resembled a surgical mask. Behind it, the chimp's eyes were curious.

You'd been deposited on a pile of furs near the cave entrance, and from your vantage point you were free to watch the apes passing by on the sheltered plateau of rock below. Their sheer numbers would've been surprise enough, but the complexity of their existence was astounding. Wood shelters joined by ladders and ramps butted up against the cliff-face, winding through and around tree trunks for support. From cooking fires and groups weaving baskets, or the faded alphabet scratched on a rock wall, there was little to distinguish the goings-on from a human village. You'd never have guessed the San Francisco apes you saw on the news all those years ago would not just survive, but flourish so remarkably.

When the bright sky began to deepen to twilight, the big green-eyed ape reappeared. The way he moved around the cave confirmed it must be his; you'd concluded from its size and furnishings, and from watching the others' behavior around him, that he must hold some position of importance.

Without acknowledging you he retrieved kindling and a flint stone from deeper in the cave and set about making a fire in the shallow pit. He completed the task with skill and ease, not the clumsy fumbling of an animal taught a few parlor tricks.

As the fire sprang to life he sat down on a ledge across from you. His gaze was laser focused, his posture still. You wrapped your arms around your knees as if for self-protection, trying to maintain eye contact.

"Tell... me," the ape began, his raspy baritone careful. "About humans."

As you tried to form a response to this broad statement, he clarified, pairing his words with signs. "How many?"

"Few," was your eventual reply. "As far as I know."

It had been six months since you'd lived with people. After the Flu everything had devolved into chaos, nothing but the mad scramble just to stay alive. After falling in with one rag-tag band after another you'd finally had enough, and taken your chances and set off on your own. It had been difficult: the scavenging for food and supplies, the sick belly when you ate something you shouldn't have, the aching loneliness. But no one was trying to kill you or steal what you had. It had been... alright.

That is, until the weather turned south, and the brisk fall days began their downward turn to the biting nights of winter.

You'd sunk into introspection, chin on your crossed arms, hypnotized by the flames' reliable orange flicker. You found the ape's eyes again. They were fierce and vivid, even in the dim light, and astute.

"Cold... nights," he observed. "You... have home?"

"I was living in an abandoned camper," you explained. "Worked great until the temperatures dropped, and it started to leak."

"Stay with apes." It sounded more like a command than an offer. "Food. Shelter."

"Wow, I – thank you." You were taken aback by the generosity. True, your heart leaped at the thought of regular meals and a warm, dry place to sleep... but you were a stranger. Another species, even, one that had been hostile to his in the past. Why would these apes extend the hand of friendship so readily?

"Children," he rumbled, interrupting your thoughts. "Young. Babies."

"Uh... babies?" you repeated, not sure if you understood correctly. "What about them?"

"Humans... still... have?"

"Yes?" It came out like a question, unsure what he was getting at.

An indefinable emotion passed across his face, and his brow grew even tauter as he regarded you intently. It occurred to you that in your time observing the village today, the only apes you'd seen had been adult-sized.

"Apes... have none." He seemed to be turning inward, searching for the words. It was clear that his lack of vocabulary had no bearing on his intelligence. "Sick inside."

"Apes are infertile?" You said it more to yourself than him, but he nodded in confirmation. The fire's glow illuminated his arresting features, and despite your uncertainty about this entire situation you found your attention glued to the striking image.

"Baby." His eyes could bore holes in you. "Human... and ape."

You blinked. Something was lost in translation.

"Male ape," he stated. His gaze flicked down to your abdomen. "And female human. Together."

"No." Your denial was strangled; almost a laugh. But his face was determined and deadly serious, as if conscious of the impact his words were having on you.

"That isn't going to work," you blurted out, as if inter-species reproductive biology was your chief concern.

He tilted his head and considered. Your heart pounded in the interim. In the end all he said is, "maybe."

"But you said apes are infertile!?"

"Most." He glanced out to the cave's entrance. "Mainly females."

"That's a bad idea," you stammered. "That's crazy."

"Necessary."

"Well, you don't expect me to...?"

"Few humans left," he remarked, repeating your words back at you, as if that explained all and his word was final.

Your hands began to tremble. The fire blurred and you lowered your head, fighting the surge of shock and failing. To your humiliation you felt hot, unwanted tears pricking your eyes.

You risked a furtive glance up at the ape. He looked... unsettled. Put off. Did apes cry? These ones must. They weren't mindless animals. And so how could they expect you to be their... incubator? It was barbaric.

You stared down, attempting to harden your expression into something as hard as the rocky ground. Was this just how their society worked? They offered food and shelter and safety, and in return you gave them... your body?

It wouldn't be the first time you'd come across the opportunity to trade sex for necessities. You had yet to take that route... but it had never been outside your realm of possibility.

You raised your head again when a shadow blocked the fire's light. The ape had crossed around it and sat now on his haunches, his eye level just a shade above yours. It wasn't caring in his face, exactly – his brow was as rigid as ever – but there was a sort of subtle empathy that radiated out from those hooded eyes. It startled and transfixed you.

"Caesar," he said, and touched his chest.

"Caesar," you repeated automatically, a mere whisper. "That's you."

The ape extended one hand and brushed away a stray tear clinging to your cheek. You flinched at the contact, so soon after the bombshell he'd dropped. His knuckle was calloused, the contact feather-light and fleeting, and he withdrew almost as soon as he'd reached out.

"You can go," he said, jerking his chin towards the mouth of the cave. "Can... leave. Not a... a..."

"Prisoner," you supplied.

"Not a prisoner."

"Can I think about it?" It sounded hollow and false even to your own ears.

He put one meaningful fist on the ground. "Caesar's home," he grunted. "Stay here."

"Okay," was all you could manage. "Okay."

But you weren't sure if it was an invitation, or an order.

You steadfastly ignored Caesar for the rest of the evening, speaking only to mutter your thanks when he brought you a wicker bowl of roasted fish. He went out again, and when he returned he retreated into the depths of the cave without a word.

Think about it!? The concept was beyond comprehension.

Humans. And apes. Breeding.

Unthinkable.

It took eons of tossing and turning to fall asleep and the next morning you remained in your spot, huddled in the furs for warmth and unwilling to get up and deal with your predicament. You'd half expected to wake up in your rickety old camper.

Caesar held court on the large ledge just outside the cave and apes came and went, conversing with him and each other. Your face burned each time one glanced at you. Could you do this? Have... sex with one of them? Did you have a choice? The thought of slogging back out into the freezing, indifferent woods made your stomach sink down into your worn boots.

Which ape would it be? By now it was obvious that Caesar was their leader, so would he be responsible for choosing? Is that what they were discussing now? Would you have to do it several times, until a pregnancy stuck?

A pregnancy. Good God! What a thought. You didn't believe anything could actually result of this or else you wouldn't even consider it.

You took mental stock of your rundown camper, with its flimsy, squeaking mattress and soggy floor, of curling as close as possible to the fire without being burned, of opening expired canned goods with a hammer and a nail. You cringed at the memories of your pitiful hunting attempts, and vomiting all night after trying some mystery berries, and walking until your feet blistered because you couldn't find a working car and your socks were soaking wet enough to squelch with each step.

The idea of mating with an animal made your gorge rise – but they were not like the zoo creatures of your childhood. You took in their inquisitive, interested glances, one after another, each alight with the spark of intelligence and understanding as they communicated with each other. You were fascinated anew at how emotions manifested on their faces no differently than those of humans. Though you couldn't understand their sign language, their expressions and body language transcended species.

The chimp in the veil returned, examining your wound and gibbering in approval. The pain had all but subsided, leaving only a small tender spot. Time would tell if it would scar; no matter either way, just another added to the collection. You wondered what would've happened had you been left to bleed on the river bank. Would you have come around a day later, cold and sore but none the worse for wear? Or would you not have woken up at all?

Your wandering thoughts were brought firmly back to reality when Caesar materialized out of the back of the cave. He finished his conversation with another ape, dismissed him, then turned your way. You should at least look him in the eye, you decided, so you disentangled yourself from the furs and stood. It was unavoidable, noticing again how intimidatingly large he was – broad, muscular, and standing an inch or two above you.

Not a zoo animal at all.

"I'll do it," you said in a rush, before nerves claimed your tongue and made you back out. Once the words are free you can't believe you'd said them.

Caesar processed this, then grunted in what sounded like satisfaction. You rubbed damp, shaky palms on your cargo pants.

"Who do I have to... do this with?" You thought of the apes you'd seen, trying to determine which of them would be the most tolerable. Regardless, you could just close your eyes and endure until it was over.

Something changed in his face, something almost imperceptible.

"With... me."

Your stomach flipped not with alarm, or revulsion, but something else you couldn't pin down. "Why you?"

Caesar's brows drew further together. "I have son."

Oh. He was a proven entity, then. That would make sense. "Who's your son? Who's his mother? Do you have a... a partner? A wife?"

Please let him not have a wife.

Caesar considered the barrage of questions. "Son is Blue Eyes." He paused before his next answer. "Not wife. Just... mate, for a while. Dead, now. In... childbirth."

How comforting. At least you wouldn't be the other woman.

"Must eat," he instructed, gruff and business-like. "Must be... healthy."

At least you would eat well. Too many times lately you'd felt yourself drifting closer and closer to starvation.

He gestured and you followed him down the wooden ramp to the plateau below. Several large cooking fires burned and he led you to the nearest. On a spit over the flames was what looked like a skinned rabbit, and a small female was tending it. She and Caesar exchanged signs, his level and hers animated, the beads over her ear clicking. Her perusal of you was wary, and you felt deeply out of place as you sat down cross-legged by the fire.

Caesar touched your shoulder to get your attention and you jumped at the contact, even through the layers of shirt and sweater and coat.

"Leaf," he said by way of introduction. "Will... give you all you need."

And with that he left.

Leaf was clearly as unsure about you as you were about, well, everything, and communication was a struggle. But she gave you the choicest morsels of meat and demonstrated how to get the rich marrow out of the bones, and outfitted you with a water gourd with a rope shoulder strap. She showed you where to refill it, and where to relieve yourself, and the closest path to both a bubbling creek and the wide and rushing river it joined. Two apes fished, jostling and horsing around in between attempts with their spears.

You did not see Caesar at all. He could be anywhere in the sprawling compound, or in the forest beyond, and it was almost a relief to get a reprieve from that piercing stare. Eyes still followed you, though, heads craning as you passed, but there seemed to be no malice in the attention. You were a novelty, and you could only assume they all knew what your intended purpose was.

Night fell earlier now and when the pair you'd seen fishing earlier brought home their catch, the silvery trout were divvied up equally. Better than you could say for the humans you'd known in recent years, who'd snatch food right out of someone's mouth as soon as share it.

You sat close to the fire to stave off the creeping chill, and ate with gusto – there seemed to be no afternoon meal here, and your belly was clenched with hunger you were well acquainted with – but though the roasted fish was delicious, you choked on it when Caesar appeared in your peripheral vision. He saw you, but did not speak to you, and ate among a knot of apes, including the orangutan you'd met and a scarred bonobo who stared at you through a milky, unseeing eye. There was another chimp, smaller and lither than Caesar, who sat close to him – his face was youthful and earnest and his gaze sky blue.

You took the opportunity to observe Caesar discreetly. It was increasingly easy to think of him as a person rather than an animal: his carriage was upright, and his rugged features – lighter in color than those of the other apes – were serious and shrewd. His name was appropriate and you wondered how he'd come by it, and about his life before the Flu.

A little hoot turned your head, and Leaf loaded up your bowl with more steaming trout.

The apes seemed to enjoy the communal aspect of eating and sat around the fires until long after dark fell before clearing away the dinner mess and retreating to individual homes. Within them, smaller fires sprang to life, dozens of little orange beacons dotting the cliff face.

Caesar's attention was on you now, like a spotlight cutting across the open courtyard. The resulting swell of anxiety almost sent your meal right back up. You hadn't had alcohol in years – when it could be found, it was smarter to trade it for actual essentials – but by God you could use a drink. Something to numb the racing thoughts, to quiet the voice of sanity that cried, what are you doing!? This all felt like the feverish dreams brought on by those wild mushrooms you'd tried once.

Maybe you should find some. It might make this easier.

Caesar's movements were purposeful as he headed your direction and you froze in your spot, feigning sudden interest in your empty water gourd as he loomed over you.

He did not speak, and his silence said everything.

"Now?" you croaked. "Tonight?"

His nod of confirmation was just a single, almost imperceptible downward tip of his chin.

You tucked your feet under you in preparation to stand, praying for trust in your unsteady limbs. He offered you his hand, and you stared at it like it was a foreign thing before accepting. His fingers around yours were calloused and warm but, as if sensing your trepidation, he released you as soon as you were upright.

Adrenaline zinged through you like electricity, throwing your surroundings into stark, hyper-detailed relief: the tightly lashed branches of the ramp winding up to Caesar's home, the distant scratching of insects in the woods, the twin torches burning brightly on either side of his cave. The entrance yawned like a mouth, flickering with shadows and ready to consume you.

And in you went.

You passed your heap of furs and moved further into the cave. Baskets and racks lined the walls, hung with nets of dried fruits and unidentified bags, and half a dozen spears in varying sizes cast a row of parallel shadows. His bed – you supposed it was technically a nest, a wide bowl woven from thin branches and lined with furs – sat on a low wooden platform on a high point in the cave, lit by the golden glow of another torch.

You swallowed hard.

Clumsily, before you could overthink it, you began peeling off your layers as if removing armor. Clothing piled up by the nest: boots and socks, jacket, sweater, flannel button-up, leaving you only in a thin camisole and your trousers. The cave floor was smooth and cool on your bare feet. When you reached for your fly your fingers stopped cooperating, the button somehow impossible to force through the hole –

You could sense him behind you, as if every nerve in your body and every tiny hair was alert in anticipation of his nearness. His fur brushed the naked skin of your upper back and a frisson raced down your spine. Each moment that passed that he didn't touch you seemed like an eternity, and when he finally put his hands on your waist, you jumped.

With light pressure he spun you to face him. His posture was restrained, the swoop of his brow so low it cast a shadow over his eyes, leaving them black and menacing in the dim light.

"Afraid?" Though his impassive features revealed nothing, his words were laced with what you would swear was concern.

"Yeah," you replied, and your voice cracked.

"I... care for apes' future." You could tell he was frustrated at his inability to express the complex sentiments necessary for the circumstances. He tilted his head, frowning, his eyes catching the light at last. The flames speckled them with gold. "But I... do not... want to cause fear, or pain."

His hands were still on you, large and steady. You searched yourself, and found no urge to push him away... and could tell the exact moment he was aware of this. Language may be rudimentary between you but in this moment, there was crystal clarity.

"No fear," he repeated, and then his mouth was on your neck. You simultaneously gasped at the brazenness of it, and stiffened at the unfamiliar sensation. With powerful arms he drew you flush against him and on reflex you clutched at his shoulders for balance. His fur was surprisingly dense and without thinking you sank your fingers into its inviting softness, without stopping to consider how he might interpret that.

You allowed yourself to be backed up to the nest and without warning he flipped you around and pushed you on all fours. The bluntness of it was a shock, even more so as he yanked your trousers down around your knees as if the sturdy fabric was as flimsy as silk. The nest creaked under his weight and his fur tickled the backs of your thighs as he shoved your panties aside, cupping your mound in his rough palm. It had been so long since you'd been touched this way, by anybody, and despite yourself your body responded intuitively to him. One thick finger slid down to circle your clit and you inhaled sharply.

Where did he learn to do that!?

It was almost humiliating, the ease with which he had you wet and panting, and you were glad he couldn't see your face. He must be doing this for practical purposes, you reason vaguely, to ensure your body was ready and receptive for him – and it was, you could feel your own slippery fluids on his massive hand, feel the heat rising in your core.

You had tried not to dwell on what his genitalia might be like but the heavy, velvety head that now rubbed against your folds felt no different than that of a human man. He mounted you with a relentless press forward, your breath escaping in a hiss as your walls stretched to accommodate him. He wasted no time in setting the pace, each thrust weighty with purpose, slamming in as if he sought to reach the deepest parts of you. His hands were firm on your waist, each snap of his hips jerking you forward, and you concentrated on bracing yourself against it. You had to push back, to counterbalance the force of his movements, and with each grind of your ass into him you felt the high, the swelling need;but inexplicably you fought it, tamping down the cresting pleasure and gritting your teeth so hard it hurt. Some part of you still resisted the taboo of this, refusing to believe you could be enjoying it despite the overwhelming evidence to the contrary –

He climaxed without a sound but you could feel every throb of his thick cock, pumping his seed deep inside you. His fingers pressed ovals into your skin, holding your body rigid until he was spent. When he released you you collapsed onto your forearms, panting into the animal hides, overwhelmed with confused and unsatisfied desire. He withdrew, and ran one hand up your back to push you gently down.

"Stay put," he ordered in a low rumble. "Be... still, for a while."

"Okay," you murmured, rolling on your side. His come was sticky between your thighs and you curled your knees up towards your chest, watching him as he rose.

There was something heated in the shameless, serious way he gazed on you, as if envisioning his seed taking hold in your womb. It wouldn't, couldn't; but the apes must be truly desperate to take this drastic option to save themselves from extinction.

With a jolt you were struck by the full extent of your relief that it was him you did this with, and not some other ape. You weren't sure you could have borne that. But Caesar – both a stranger and another species – was, with his human-like features and keen gaze, somehow... different.

Whatever his thoughts, he kept them to himself. He sat alone by the fire, and as you watched his back silhouetted in gold, your eyelids grew heavier and heavier of their own accord until you could fight sleep no longer.