Something small and solid ricocheted off the ground and bounced off the wall, spinning into the darkness. Ari regained her balance and straightened up. Mina was still on her feet, an intense look of concentration on her face.

"She uses poison," she whispered. "She can make organic liquid into poisons, so don't touch her! And anything she throws will probably be poison-coated, so be careful!"

Ari nodded, keeping an acute eye on Vexi on the floor above. The tiny girl behind her didn't move but watched with huge eyes.

"They're small, grey pellets. She fires them from her gun," Mina said, lowering her hands. Vexi looked furious, her gun pointed at the two.

"Mina might be able to phase through it, the little cow, but you can't, Transformer."

The name grated on Ari, but she didn't have time to rebut. Vexi trained the gun on her and fired. Ari barely managed to spot it in the dim light and duck. A tick behind her indicated the pellet had missed and hit the wall. Ari narrowed her eyes. She saw the next pellet flying. She flicked her finger. A small blast of air emanated from her fingertips and breezed against the pellet, sending it off-course. It joined its comrade against the wall.

Vexi's eyes bulged.

"I'm not sure if you paid attention in physiology, Vexi," said Ari drily. "I might not be able to generate huge amounts of energy, but the human body does generate some. As long as I eat, I produce energy. Probably not as much as the generators, neither do I eat as much as the generators do to maintain their energy output, but I can still fight without a plug."

Vexi turned an even darker shade of purple at Ari's words.

"Insolent smart mouth," she muttered, scowling. She fired a quick succession of pellets, all of which Ari rebuffed. It was lucky Vexi's ammo was so light and required little energy to deflect. If they had live ammo or concentrated energy lasers, Ari wouldn't have been so sure she could absorb or even deflect them. Her muscles ached and her energy level was getting quite low. It would be a challenge to take down Vexi to move ahead without a source of energy, but there was no way of retreating, not after they've sealed themselves from the dome and Kena's monsters out and about.

Vexi grew more and more furious with every failed shot. Her whole body shook. Her facial features twisted, teeth gnashing.

"Why don't you just die?" she shouted.

"That would be awfully inconvenient for some, including me." Ari's attempt at sounding light-hearted began to tire.

Mina tucked her hand in Ari's. There was the slightest tremor.

Vexi's arm shot out and snatched the tiny girl beside her, who squeaked in terror. A horrifying grin replaced the anger on Vexi's face. The tiny girl wriggled in vain.

"Plea!" Mina called, anxious.

"I'd like to see you dodge this," said Vexi, eyes glinting. Plea, the tiny girl, let out a wail. Her arms and legs stiffened. Her eyes rolled in their sockets. Vexi dug her fingers into Plea's arms. Even from this distance, Ari could see the prominent dilated veins all over the young User. Vexi, a vicious look on her face, shoved Plea in front of her and then kicked her in the back, sending the limp girl tumbling over the edge of the high block towards Ari and Mina.

Mina made to dash forward and catch her.

"No!" Something wasn't right. Ari yanked Mina back and wrapped her arms around her, panic rising in her throat. She had no energy left. The door behind them was too far away.

"Ari!"

Ari snapped her head up. A blast of electricity careered at her. She raised her hand out of instinct. The warmth of the energy she recognised – it was Fris. Absorbing it, her core energy peaked. She bent her knees. Gripping Mina tightly to her side, Ari leapt. The stored energy became kinetic, rapidly converting to gravitational potential when her feet landed on the vertical walls before she kicked off again, gaining more and more gravitational potential energy. Mina squealed, clutching Ari with all her might. Stagnant air coursed over Ari's sweaty skin as she soared. She bounced across the walls, leaping over Vexi. Ari focused on keeping the energy levels steady; managing both her and Mina's weight made the calculations more difficult. A dull explosion sounded in the background.

Easing each breath out with care, Ari skidded down the walls near the top, releasing the excess energy through her feet, landing three blocks above Vexi. Her body tingled, exhilarated by the peaks and troughs of energy she just had and rejuvenated. Mina let go and released a shaky laugh.

"So that's why you like jumping so much," she said. Her eyes caught the bottom of the laddered steps and she let out a small cry. Covering the bottommost level where she and Ari stood several seconds before was a large splatter of bubbling brown-black matter. Only the stained clothing and clumps of hair indicated those were the remains of a once-living person. "Plea!"

"Human bomb, huh," said Fris, appearing beside Ari. Ari tensed. Fris raised her hand in a peace gesture. "Relax, Ari. I'm not here to hurt you. I know better than to give you energy to attack you."

Ari relaxed a little, but still kept a wary eye out.

"Look at what you've done, Mina!" called Vexi. Her voice echoed down the long room. She pointed at the ground level floor. "Plea died, because of your disloyalty. If you hadn't betrayed us, she wouldn't have turned out like that."

What a twisted girl, thought Ari. Beside her, Mina quivered. Ari grabbed her hand and squeezed it.

"Don't listen to her. She's a psychopath. She injected Plea with that poison. It's not your fault."

"How does it feel to be a murderer just like your sister?" taunted Vexi, eyes bright, wholly unaffected by the scene behind her. "And look at you, Fris! Another traitor. I knew you didn't have the guts to carry through with any of this. How pathetic, the two of you. This is why you two will always be so weak. You don't respect yourself enough to do what needs to be done!"

"I think it's time to wrap this up, Ari," said Fris, giving her a side glance. Her red hair had come out of its usually pristine plait and she looked like she'd been in a fight recently, too.

"You read my mind."

Fris raised her hand. Ari released Mina's hand and guided her aside, out of harm's way. She lifted one hand, using the palm to face Fris to absorb maximum energy, and pointed at Vexi with her other one. Crackles filled the air. Shadows danced on the wall as Fris closed her eyes and focused, two fingers touching her temple and two fingers of her other hand poised at the ready. Her hair crackled with energy.

With a crack, electricity jumped from her fingertips onto Ari's palm. Energy surged in Ari's body and concentrated on Ari's fingers. Ari stored the energy at the tips for a few seconds longer and then sent a jolt of electricity at Vexi, who barely dived away in time. A charred black mark and cracks in the concrete remained on the ground where she once stood. The second blast caught Vexi's leg. She twitched, crying out, and her body stiffened. Her hair stood on end in its ponytail. She slammed onto the ground. The rest of the energy coursed through the ground, leaving more cracks. She struggled onto her feet after a few seconds, her breathing laboured. It was obvious her muscles wouldn't obey.

Ari concentrated Fris's next jolt of electricity even more, minimising waste through heat and sound.

The third and final blast caught Vexi in the centre of her chest as she fought to stand straight. For a moment, surprise lit up her young face. And then she collapsed like a broken toy, and remained still. The overwhelming scent of singed hair filled the room. Ari panted, weariness settling in earlier than she'd have liked. Her heart banged against her ribcage. Mina whimpered in the corner. Ari went over and wrapped her arms around her sister. Mina's shoulders shook but she didn't cry. She swallowed loudly a few times and then pushed Ari away, a determined look on her little face.

"We need to carry on."

Ari gave a small smile and turned to Fris, and froze.

"I'm sorry," said Fris at once, blushing to the roots of her red hair. She picked at the ragged dress she wore, so different from the flawless look she usually sported. "I can explain. I never meant to harm either of you, I swear. Hine asked me to join this... cult. That's probably the best word to describe it. Initially it was to better myself, and I wanted it desperately... I never realised how extensive they meant when they said we were to gain power. They were so brainwashed. It was such a small echo chamber, and the resentment and anger grew and grew. I didn't know we were killing other Users for this, but by the time I knew it was too late."

"You're not...?"

"What? No! Of course not!" Fris appeared horrified at the suggestion. "I stayed because the young ones needed me and needed protection. I didn't want a transplant. Heck, I'm considered too powerful to warrant one, and you know I'm only a Rank C. You know me, Ari. I would never want to harm people for my own gain."

True, that certainly wasn't the Fris Ari knew, but with recent changes in people she thought she kind of knew – Hine, other under-achievers – how was she to judge character anymore? But Fris seemed sincere and it was almost like back to the old days again.

"We need to leave. Now. Kena's releasing creatures from her failed experiments and they won't hesitate to kill us."

Fris's face turned white. "There is an emergency exit if we get to the top of this and keep moving. It's electronically sealed usually, but someone's downed the remote system for the past few hours so it should be unlocked."

Ari had a shrewd idea who the culprit was. She helped boost Mina up the rusty ladder before climbing up herself. Fris yanked her up the last two rungs. Ari's hands tingled when she let go of Fris's hands. It really was like the old days again.

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