And then she felt Penn’s teeth tearing through the flipper of her tail. She glanced back long enough to see that Penn had torn it right off, and a thick stream of blood poured out from the gaping wound where her flippers should be.

Gemma pushed, though much more slowly without the tail; and then she was so close, it was barely deep enough to swim anyway. The rocks at the bottom scraped against her belly, and she pulled herself forward.

As she came out of the water, she was actually crawling up, pulling herself onto land with hands and elbows digging into the sand. Realizing how slowly she was going, she knew she couldn’t outrun Penn, and she was wasting her strength.

Gemma rolled over onto her back, the cold sand sticking to her, and tried to catch her breath. Then Penn’s head appeared over her, the sunrise backlighting her face so it was impossible to read her expression, even when Gemma squinted at her.

Then Penn laughed and rolled away. Gemma pushed herself up, so she could see what was going on. Penn just lay on the beach next to her, with her face fully healed and an odd smile on her face.

The waves were lapping up to their belly buttons, so both of their tails were still in place, submerged in the shallows. Gemma could feel hers tingling and fluttering, but she wasn’t sure if that was because her tail was trying to shift back into a leg or because it was hurrying to regrow its fin.

“Too easy,” Penn said, as Gemma stared down at her in confusion.

“Too easy?”

“You fought harder than I thought you would, I’ll admit that,” Penn said with a sigh. “But that’s not saying much.”

“Why didn’t you kill me?” Gemma asked.

Penn looked up at her. “Did you want me to?”

“I just don’t understand why you wouldn’t.” Gemma shook her head in disbelief. “You hate me, and you killed your sisters Aglaope and Ligea, not to mention Lexi. You even killed your own father.”

Penn narrowed her eyes. “How did you know about Achelous?”

“Lexi told me,” Gemma lied.

There would be no way for Penn to fact-check that, and Lexi had told her that Achelous was dead. She couldn’t tell Penn about Diana, not so much because she didn’t want Penn to kill the goddess, but because in a rage, Penn might take out Lydia and Marcy, too. Her vengeance didn’t always make sense.

“My father was a selfish, narcissistic man whore.” Penn closed her eyes, apparently satisfied with Gemma’s answer, and she folded her arms behind her head. Her tail flapped languidly through the water. “He deserved what he got.”

“That still doesn’t explain why you didn’t kill me,” Gemma said.

Penn waited a minute before quietly saying, “I promised Daniel I wouldn’t.”

Gemma knew that was true, but she was surprised that Penn was actually holding up her end of the bargain. Especially after Gemma had antagonized her.

“Are you in love with him?” Gemma asked.

“Love is a bullshit human emotion.”

“He doesn’t love you,” Gemma said, and she wasn’t even sure why she did. Maybe in defense of her sister Harper, whom Daniel really did love, or maybe just so Penn would know that she hadn’t won.

“He can’t love me,” Penn corrected her. “But there might be a way around it. If that stupid Alex kid loves you, there has to be a way for me.”

“You can command someone to do anything except love you, Penn. Alex’s love is real, just like Daniel’s love for Harper. How could he ever love something as awful as you?”

Penn went on, undeterred. “I have my ideas.”

“Has anyone ever loved you in your whole entire life?”

“You’ve got me all figured out now, don’t you, Gemma? Mommy didn’t love me. Daddy didn’t hug me enough. If only you could just understand me, then I’d give up my life of evil and save the world.” Penn glared at her and scooted back onto the beach, pulling her tail out of the water.

“It’s all a load of crap, Gemma. Do you know why I’m going after Daniel, why I’m going to have sex with him, and why I’ll eventually tear out his heart?”

“Because you can?” Gemma asked, as Penn’s tail shifted back into her long legs.

She’d been wearing what appeared to be a tight tank top, but when Penn stood up, pulling the wet fabric down past her hips, Gemma realized it was a minidress.

“That’s right.” Penn flashed a dazzling smile and bent over, so her face was level with the still-sitting Gemma. “And I love it. The one thing in life I still enjoy is the hunt. Chasing down what I want at any cost and getting it. And then just throwing it away once I’ve had my fill.”

“That’s an empty way to live, Penn.”

“Oh, fuck off, Gemma.” Penn rolled her eyes and stood up. “Like I care what you think. You think Alex is a catch. And I don’t care where you went today. It was probably a quilting bee, knowing you and your stupid friends.”

“You know me, and how much I love quilting,” Gemma muttered.

“Right now, I want Daniel, and he wants me to keep you safe. So I will. But how much longer do you really think I’ll be interested him? Hmm?” Penn waggled her eyebrows. “And then your human shield will be all gone, all chewed up. And I’ll really show you how to behave.”

Penn turned and walked up the beach, away from the rising sun, and left Gemma alone in the sand to nurse her wounds.