The human was distressed. She stood in front of Alpheus's tank, gesticulating. Yes, that was the word for it. Gesticulating. Fluid fell down her face. Tears. Tears meant one or more things:

Alpheus removed three of the five possibilities. This human, Melissa, had no allergies or tear duct abnormalities as far as he knew. Alpheus's room contained no onions. There was a concrete ceiling, a concrete floor, concrete walls and a glass tank. No drain holes in the floor. The water for his tank came and went through a series of ultrafine tubes, only the width of a few molecules of water.

The humans worried he would escape from a bigger tube. He knew this because Melissa told him and in Alpheus's experience, Melissa's statements were 87% accurate. This assumption that he could enter a tube any smaller than a human finger was erroneous. Alpheus may be one of the more advanced cephalopods but he had yet to master that level of corporeal deformation. He had tried to tell Melissa this but she mistook his skin flashes and airborne colours as anger.

For humans, red = anger/danger.

They couldn't see all the different reds.

The ones that mean difficult

or still trying

or unreachable goal

or there is no point pursuing that avenue because the cost-benefit ratio is too high.

Although Alpheus had to admit that in this particular case, the benefit of escaping through a nanotube could well outweigh the cost of acquiring that skill.

It was most likely, therefore, that Melissa was sad. Teal leaked out of her skin into the air. It tasted like regret. Alpheus did not want Melissa to be sad. She was his favourite human. The appropriate remedy for human sadness was a hug. The good thing about hugs was that they were also appropriate for happiness. Therefore, Alpheus did not need to waste time calculating whether Melissa was happy or sad. He launched himself from the bottom of the tank and wrapped four of his eight arms around her.

She laughed. Laughter was good. It was almost always a sign of amusement or happiness:

For good measure, Alpheus reached the tip of an arm under Melissa's armpit and tickled. She giggled and pushed his arm away, then wiped her face with her hand. Her skin now tasted like happiness and sadness. Poignant.

Melissa liked words. Alpheus liked words. Humans couldn't taste or see the chemicals emitted by all living creature so they invented sounds to label things, then created letters and words to represent these labels, and slapped these labels onto animals and plants. Alpheus was an octopus. He was a problem-solver. A trickster. A few months ago, he became an alien.

"I'm so sorry," Melissa said.

She stroked his head. Her fingertips were rough and they tasted like guilt. Alpheus kept hugging her even though she felt uncomfortably warm. He stretched two of his arms down to the ground and balanced on them like human legs.

"You're the last one left."

Tears dripped onto his head. They tasted like his tank water.

"They're going to take you away tonight. They – they'regoingtoeatyou." The words rushed out glued together and almost swallowed by sobs.

Alpheus's skin flashed white. Alarm. He did not wish to be eaten. Not by a human.

"I can't even smuggle you out. There are cameras. They're watching us, and Prof Lopez said if I kill you, I'll be arrested."

Dark red rippled across Alpheus's body and out into the air. He stretched his body up tall and spread two of his arms out wide. Why would Melissa kill him? They were friends.

"It's my fault. I should never have told them what you said about C-Pod."

Alpheus had invented C-Pod during their daily game. Melissa would use words to ask him questions:

"What do you like?"

"What do you dislike?"

"What is your favourite food?"

and he would answer with colour. She decoded his messages into words with a little chemical sensing, photoimaging machine. A translator. He liked this game.

One day, a few months ago, she asked, "Where do you come from?"

He tried a joke. Melissa had explained jokes. Humans sometimes said things that weren't true and other humans laughed. Alpheus liked it when Melissa laughed. The room became yellow and her skin tasted like sunlight.

"I come from a planet called Cephalopodia," he said. "We, the inhabitants of C-Pod, are shepherds of the universe and we are here to make sure the Earth survives."

She didn't laugh at his joke. She covered her mouth with her hand. Later that day, the older human, Diego Lopez, appeared and asked Alpheus the same question.

"Where do you come from?"

Alpheus was hungry now and not in the mood for joking. Also, he did not like the Diego Lopez human. The translator spat out his answer:

"I want crab."

"Not until you answer my questions."

Alpheus squirted Diego with tank water. Diego stood, dripping, in front of Alpheus's tank. He creased his eyes and mouth into thin lines. Grim. Then he turned and disappeared out of the only door into Alpheus's room. That door was always locked. Alpheus had tried many times to pry it open but even his eight limbs and 2140 suckers were no match for the hermetically sealed metal.

Diego reappeared seven minutes and 34 seconds later. He carried a large flask containing a blue king crab. The crab twitched inside the flask and emitted dark blue distress chemicals. The diameter of the flask opening was 1.46 times smaller than the width of the crab's body. Diego must have forced the animal inside. It was another game. Diego dropped the flask into Alpheus's tank.

"What are you doing?" Melissa said, staining the air vermilion. "It's not time for that test. He'll never be able to get the crab out. Making him angry won't get him to answer your questions."

But Alpheus wasn't angry. He was intrigued. His whole tank tasted like crab and taupe-coloured fear. Alpheus slid a tentacle into the flask and caressed the crab.

"Hello eight-legged friend," Alpheus said. He spoke in colours off the spectrum of the human's translator.

"Don't eat me," the crab said.

"I'm afraid that I am culturally and situationally bound to eat you since the humans have presented you to me as food."

"Perhaps you could eat a human instead?"

Alpheus would enjoy wrapping his arms around the Diego Lopez human, squeezing the air out of him and sucking his succulent flesh, but he did not wish to be forever tainted by Diego.

"You could pull me out and I'll pinch the old one's nose while you squeeze the young one then we can both escape out the door. I know the way back to the ocean."

Alpheus slid another arm into the flask. The flask neck was much too narrow to try and pull the crab out. He compressed his body until it flowed through the neck down into the flask and around the crab.

"I will not eat you, friend," Alpheus plunged his hard beak into the crab's back, striking the main nerve centres. "I will honour you by subsuming your past into my future. Crab will become octopus jumping four orders of evolution."

He ripped the crab in half, then squeezed his body out of the flask, bringing the crab halves with him. He sat on the bottom of his tank and scooped out soft crab flesh.

"Less than a minute," Diego said. His words came out as puffs of orange.

Melissa stood beside him with her arms crossed. Vermilion still swirled around her.

Diego waited until Alpheus had sucked out the last of the crab from its carapace. "Now, where do you come from?"

Alpheus bobbed his head up above water. "I come from the ocean."

"What does the ocean on C-Pod look like?"

"All oceans look the same."

"When did you come to Earth?"

"I've always lived on Earth."

"When did your parents come to Earth?"

"I've never met my parents."

"Who are the shepherds of the universe?"

"No one can shepherd a universe that does not wish it."

"Why won't the Earth survive?"

"Nothing survives forever."

Diego's words were no longer orange. They were now dark purple. Alpheus lifted an arm out of his tank and shot yellow into the air, watching it thread through the purple cloud around Diego.

"Make sure that transcript is backed up." Diego stomped out of the room, clanging the door behind him.

Alpheus had not seen the Diego Lopez human since. Each day Melissa asked him about C-Pod. He embellished the story more and more. He wanted her to smile.

Melissa reached her stiff arms around Alpheus and hugged him back. "I'm here to say goodbye to you, Alpheus. This is the last time I'll see you." She emitted peach-mixed-with-coral that Alpheus was sure was off the translator spectrum. It said I am not giving up.

Alpheus moved several of his arms to cover Melissa's. Then he pinched off the lower part of his mating arm. He hid it inside their hugging forms and handed the hectocotylus to Melissa. Her pupils dilated. She knew what it was. She coiled the arm into a stack and hid it inside her lab coat. Alpheus extended one side of his body so it hung down like an extra leg.

Then he dropped to the floor and slithered back up the side of his tank. He hovered at the top of the glass.

"Goodbye, Melissa," he said.