Darkness, and the pressing sensation of thick, warm fluid all around her. Carla could hear whistles and echolocation clicks echoing through the liquid, and fired off some of her own. The returning echoes revealed long, thin shapes all around her: other Yeerks, she realised. Carla instinctively began to extend and contract her body, swimming towards a scent she recognised. Somehow, she was able to communicate, to call in the squeaky, otherworldly language of Pool Yeerkish.

"Silrin, wait!"

Her echolocation detected the other Yeerk pause and turn back towards her, swimming close to brush her palps across Carla's own.

"I've missed you," she heard the Yeerk reply. "It looks like you're one of us now. Welcome." Silrin twined her body around Carla's slowly, an intimate gesture performed only between close siblings, friends or mates. Carla felt herself reciprocating the gesture, releasing chemical signals to communicate her joy.

Suddenly, the water began to swirl irregularly, sucking them down towards the centre of the Pool.

"What's happening?" Carla tried to squeak to Silrin, but the other Yeerk was being ripped away from her by the current. Confusion was all Carla felt for a few seconds, as the water began to pull more insistently at her body, but then she understood. The cleaning cycle! But how… why… wait, she knew this. Jake! Jake was flushing them… they were all going to die!

"Silrin!" Carla felt her body contract with terror, could smell her own stress hormones being released into the water around her, as well as those of countless others, as she continued to be sucked down towards the blackness of space. "Silrin! No! No, Silrin! Come back! Silrin, no!"

Carla opened her eyes. Someone was bending over her in the darkness, shaking her shoulders gently. "Silrin?" Carla muttered, confused.

"No, it's me. Alniss. I'm sorry."

Carla struggled to focus on Alniss' face, pulling herself up into a sitting position. The light from the streetlamp outside was leaking around the edges of the curtains as it always did, casting long shadows onto Alniss' concerned face. Tugging at the neck of her soaked pajama top, Carla tried to get her breathing under control.

"It was just a nightmare, honey." Alniss' hand was running comfortingly up and down Carla's back as she pulled her to rest against her body, seemingly heedless of the sweaty mess she was in. "It's okay."

Carla shook her head. "It wasn't just a nightmare. She's… she's gone."

"I know. I wish I could change that."

"So do I," Carla whispered wistfully.

They sat in silence for a while, Alniss' hand stroking slowly against her back, her hair, her shoulders. Carla felt the sensation of panic beginning to fade, but it was replaced with an intense, desperate sadness.

"Do you-" Carla stopped herself. It wasn't fair to ask Alniss that question, she had to remember that Silrin had been her schrellie, one of the closest relationships Yeerks had. It wasn't fair to make her grief worse.

"Do I what?"

"It doesn't matter. I just wondered- it's nothing."

"Wondered what?" Alniss pulled back a little to look searchingly into her face. "You know you can ask me anything."

Carla shook her head insistently. "It isn't fair on you."

Gently, Alniss smiled at her. "I don't think bottling grief up has ever helped either of our species to process it. Let me help you. If you feel you want to ask it then it's probably something that it would help you to know. What is it?"

Carla swallowed and looked away. "I… I just… do you think she knew what was happening?" Carla was forced to stop, taking a few gasping breaths. "At the end, I mean. Did she know she was going to… to…"

A deep, sad sigh was the only response Carla got for a few seconds.

"I- part of me wants to lie to you, Carla, but I don't think it would be right." Alniss hesitated, touching Carla's shoulder.

Carla looked around to make eye contact, which seemed to give Alniss the courage she needed to carry on.

"Yes. Yes, I'm sure she would have worked out what was happening."

Carla looked away quickly. She felt like she couldn't breathe, but managed to gasp out another question. "How long for? Did she… did she suffer for long?"

Again, Alniss hesitated for a few moments. "That depends on where she was and how quickly she worked out what was happening. Yeerks can sense quite small changes in currents, and the ones to drain the Pool would have been quite forceful. The cleaning cycle takes around fifteen minutes, so that's the longest she could possibly have known for, but if she was near the bottom of the Pool when it happened, it might only have been…" Alniss paused, taking a few deep breaths. "It might only have been a minute or so. If that."

Carla began to sob again, and soon heard Alniss join her. She reached for the Yeerk's hand and held it tight, pressing her body against Alniss' and burying her head into her shoulder. Each of them, almost at the same time, reached with their free hand to squeeze tightly around the other's shoulders.

"I'm sure she thought of you," Alniss whispered after a while. "She would have wished she could thank you for what you did for her."

Carla swallowed, pulling away a little to wipe at her eyes with the back of her hand. "I didn't do anything, or at least not anything that special."

"You did. With Elsa, Silrin was a total mess, she was under so much pressure. Every time I met her in the Pool she was gil'hin… I suppose the human equivalent would be crying. When she got you, I got my sister back."

For a few minutes Carla sat in silence, absorbing that information. She'd known that Silrin had had an involuntary host and hadn't enjoyed it, but she'd had no idea how strong those emotions were. The thought of her Yeerk crying every time she got a few moments to herself made Carla's insides twist into knots.

"I didn't know," she said eventually.

Alniss looked hesitant. "Maybe I shouldn't have…"

Carla shook her head forcefully. "No. No, I want to know."

"Okay," Alniss said softly, letting a hand stray up from Carla's shoulder to stroke her hair.

They sat there in silence for a while. Carla could feel the dampness from her own tears in the cloth of Alniss' bright green pyjama top, and feel her still-unsteady breathing against her hair. She felt her own breaths gradually begin to slow as she concentrated on the sensations around her, including Alniss twining a lock of hair around and around her finger, letting it go occasionally only to start again. It was a strange, repetitive motion, something intimate yet not like something a human friend would do. Despite its oddness, Carla found it comforting, allowing herself to breathe out a deep sigh. She could feel some of the tension draining from Alniss' body, too.

"Thank you," Carla whispered without moving her head.

She felt Alniss touch her cheek to the top of her head. "Thank you," she replied simply.

Carla yawned widely. Without a word, Alniss pulled back from her, shifting to turn back the duvet on Carla's bed. In similar silence, Carla lowered herself back down onto the comforting pillows, letting Alniss tuck the duvet around her and squeeze her hand gently in a silent 'goodnight'.

The rest of the night passed peacefully, without nightmares.