Within a few seconds of their going underwater, Penn decided she’d had enough of Gemma’s talons around her throat. She bared her teeth, letting out a low, guttural laugh, and gripped Gemma’s arms.

Gemma’s arms had lengthened, stretching the skin tight around the bone, so when Penn grabbed her, digging her sharp talons through her flesh, they actually pierced the bone. Gemma cried out in pain, and Penn pushed back, sending her crashing into the stone wall of the bottom of the rock Gemma had been clinging to.

Penn’s mermaid tail had been pumping with such ferocity that when she slammed Gemma into the rock behind her, Gemma was surprised that the massive stone didn’t give way behind her. Reflexively, she let go of Penn’s neck, then, quickly, Penn pulled her back and slammed her into the rock again, cracking Gemma’s skull against the stone.

Pain shot through Gemma’s head, and for a second, she saw white. But when that cleared, Penn’s cackling face hovered in the water in front of her, her wispy black hair floating around her like a dark halo.

That evil Cheshire grin was all the motivation Gemma needed. She’d always wanted to smack that hideous smile right off Penn’s face, so she finally did.

Before Penn could slam her into the rock again, Gemma slapped her hard, letting her claws rake across her face as she did. When one of her talons pierced Penn’s eye, she cried out in pain as blood reddened the saltwater around her.

Penn let go of Gemma so she could cradle her own face in her hands, and Gemma dove at her again. Balling her long fingers into oversized fists, Gemma began pummeling her. Since her bones were like marble, it was like punching with brass knuckles.

Penn’s arms were shielding her face, so Gemma focused her attention on the soft, exposed flesh of her stomach, and she slammed her fists into it over and over, hitting her abdomen and her sides. Penn swam backward as Gemma hit her, and it wasn’t until Gemma punched her chest, hitting her in the ribs directly over her heart, that Penn reacted.

She lunged to the side and tried to swim around Gemma. Gemma turned with her, thinking Penn was trying to get away, but then she felt a long arm around her neck, coming from behind her, as Penn put her in a headlock.

“Don’t even think about going after my heart,” Penn growled, her demonic voice right in Gemma’s ear, and she tightened her arm on her throat, suffocating Gemma.

Gemma craned her neck and gnashed her teeth, biting at anything she could. Her jagged fangs tore into Penn’s shoulder, ripping off the flesh and scraping against the bone. Penn moved her arm to get it out of the bite zone, and Gemma wriggled free.

As she swam away, she used the considerable strength of her fish’s tail to smack Penn in the face. Penn roared and began to swim upward, so Gemma gave chase. Penn wasn’t that far ahead of her, and Gemma reached out, trying to grab her.

Her talons dug into Penn’s hip, and Penn sprinted ahead. Gemma refused to let go, though, so her claws raked down Penn’s side, ripping scales off as they tore through her tail.

Penn reached the surface first, and Gemma heard her cursing through the water. When Gemma came up a few feet away, Penn was tilting her neck to the side, cracking it. She was surprised to see that Penn looked almost human now, other than the sharp teeth protruding from her mouth.

The scratches on her face had mostly healed, and other than a dark line across her eye, there wasn’t much left of the injury. That’s why Penn had shifted back to human—the transformation sped up the healing process.

Gemma had her own healing to contend with, and she allowed her face to slowly shift back. But, like Penn, she kept her fangs out.

“So you really wanna go for it, Gemma?” Penn asked, and her usual wicked smile returned. “I thought I’d let you get a few slaps out, burn off a little steam, but you really wanna do this?”

“I want this over with,” Gemma said, and she was surprised at the inhuman growl in her voice. The monster was out, but she was still in control.

“You really wanna die today?”

“I won’t be the one dying,” Gemma said, and she dove at Penn and punched her right in the mouth.

With blood dripping from her lip, Penn snarled and reached out, grabbing a clump of Gemma’s hair. She knotted her fist right at the base, with her claws scraping the skin, so if Gemma were to pull free, Penn would rip her scalp off her head.

She whipped Gemma around, so her back was pressed to Penn’s chest, and as Gemma trod water, she felt her tail brushing up against Penn’s. Penn yanked her head backward, and she pressed a talon into Gemma’s jugular.

Gemma grabbed Penn’s arm and tried to pull free, but it was like trying to move concrete. When they had been fighting earlier, Penn had to have been holding back, but right now, it had never been more clear how much stronger Penn was than her.

“You stupid, weak girl,” Penn sneered, as Gemma took shallow breaths, trying not to press the talon any deeper into her skin. “You never eat. You never change form. You’re starving and useless. Did you really think you stood a chance against a powerful, well-fed siren like me?”

“I thought it’d be worth a shot,” Gemma admitted.

“Did you know that this is exactly how I tore off Ligea’s head?” Penn asked. “I gripped her hair just like this”—she tugged on Gemma’s hair to show her—“and her head just popped right off. And I can do the same to you right now. So I’ll ask you again—do you really want to die today?”

Even though, a few minutes before, Gemma had thought she didn’t care if she lived or died, with her death feeling increasingly imminent and her heart pounding desperately to live, she knew she had to do something.

Instead of pulling against Penn, she decided to give in to her. She stopped moving her tail, going limp in Penn’s arms, and leaned back against her. Confused, Penn started to go under before pushing herself upward.

With her hand still buried in Gemma’s hair, she tried to pull Gemma up with her. But Gemma slipped beneath, so Penn’s talon sliced sharply across her neck and chest as she jerked away.

Gemma twisted around, yanking Penn’s arm into an unnatural position. Clumps of her hair and scalp were tearing way, but she’d finally put enough distance between Penn and herself that she could turn and bite Penn’s forearm, sinking her razor teeth in the sensitive part just above the wrist, tearing through the tendons and cracking into bone.

Penn howled and finally released her, and Gemma took off, swimming as fast as she could toward the shore. She didn’t really have a plan for when she got there. She just knew she had to get away from Penn if she wanted to live to see another day.