Caitlin stared back at him for a moment, frozen, and then sat up straighter, shuttering her eyes to him.

"Are you okay?" she asked anxiously. "Did something happen? Are you hallucinating again?" He raised his eyebrows nonchalantly. "What's going on?"

"You tell me." He folded his arms.

She stared back at him incredulously. "What are you talking about?"

"Why don't you ask Harry?" Caitlin's eyes widened, and Cisco peered at her to decipher the expression in her eyes- Panic? Anger? -but she composed herself in seconds. He decided to poke the hornet's nest again. "Or, better yet, skip the middleman and do an EEG so you can see right into my thoughts?"

Caitlin twitched apprehensively. "First of all, that's not how an EEG-"

"Caitlin!" he growled, frustrated. She tensed up, startled by his aggression. He sighed, trying to calm down. Fighting wouldn't get them anywhere. "Please. The truth."

Her nostrils flared slightly and she crossed her arms. "Right, because you've been so honest with me lately," she said hotly, and that stung, because he knew she was right.

He took an inhale. Long, deep yoga breaths. Wax on, wax off. "But I came clean eventually," he said coolly. "So."

Caitlin stared at him blankly, chewed her lip for a second, and then kicked the ground so that the chair she was in swiveled to face him.

"It's not what you think it is," she began, reluctantly.

"I have no idea what I think, so you probably shouldn't lead with that."

Her eyes darted around nervously, like a cornered animal looking for an escape route. She's evaluating the repercussions of what will happen if she tells me about her little scheme. Or trying to think of another lie to tell me. Instead, the muscles in her face relaxed, and she leaned forward, still holding a fair amount of tension in her arms and back. "Where should I start?"

"I have several questions." Caitlin nodded, permitting him to continue. He took a short breath. "First of all, how; secondly, why; and third, how the everlasting hell did you manage to tweak a phone to bypass the vibrational outputs of the Multiverse?" Her face twitched, as if it amused her that that was what he wanted to know. "Seriously, I've been trying to do that since last year, when I realized Harry was definitely going to leave us at some point, and I've been tinkering like crazy- or was, until I gave up. All I have to show for it is a pile of jacked-up Nokias in my workshop."

Caitlin picked up the weird phone-thing and turned it over. "Harry gave this to me the first time he and Jesse left, after we defeated Zoom." She handed it to him, and he gazed at it, slightly awestruck. He turned it over in his hands, tracing the wires with his fingers, trying to make heads-or-tails of what it was or how it worked, but that was typical Harry, always two intellectual lightyears ahead of them. He handed it back to Caitlin, but made a mental note to steal it later so that he could take it apart and try to replicate it.

"Why did he give it to you?" he asked, looking up at Caitlin. "Why not me, or Barry, or all of us?"

"Harry said to only use it for emergencies," Caitlin said, and carefully set it back down on the table. "Metahuman emergencies. And I was the only one without powers, at the time." Cisco felt the blood drain from his face as he realized what she was saying. "He gave it to me to-"

"To protect you," Cisco murmured, and felt cold all over. Caitlin nodded solemnly. It made total sense, because Harry had seen the even more harrowing ramifications of Zoom's reign, and he'd been face-to-face with Reverb.

Caitlin was studying his face, reading him. "It's not like that," she said hastily. "I don't think he had any real concerns; it was more of a fail-safe. You know Harry, he always has a contingency plan." She fidgeted with her hands uncomfortably.

He had to stomp on the urge to say And so do you. He took another deep breath- wax on, wax off. "Okay. So that brings us to why."

She folded her hands in her lap, as if that was the only way she could keep them still. "I called Harry yesterday because I was concerned about how your powers were affecting you, and I needed a second mind." Caitlin turned back to her desk and gathered a few papers from its surface. White papers with black bumpy lines- the EKG? "When you passed out the first time, I drew some blood and ran standard analysis, because we had no idea why you passed out and I wanted to make sure you didn't have any major medical issues that we weren't aware of." That was how she had known he was dehydrated, he realized. "You had fairly high levels of troponin in your blood- that's protein from your cardiac muscles."

"Isn't that a sign of a heart attack?" he interrupted. He may not have gone to med school, but he'd watched enough episodes of Grey's Anatomy to know what the signs of a heart attack were.

She nodded. "Yeah. I did an EKG, but it came back normal, and your vitals were normal, so I dismissed it as an anomaly. Then that night, when you came through the breach into my apartment, your heartrate was way too fast. Any other person would have had a stroke before their heartrate got that high, so I realized that it must have something to do with your powers. When you were asleep in the med bay this morning, I did a polysomnogram to see if you went into REM- like you have in the past, remember, before we even knew you had powers we induced REM so that you would Vibe-"

"But you gave me a sleeping pill," he inserted. "Wouldn't that affect the outcome?"

She shook her head. "I gave you a placebo, but you never went into REM, anyway."

He leaned against her desk. "What exactly is your theory?"

"I was getting to that." She glanced down at the papers in her hand again. "In your apartment earlier, when we were talking, you went into some kind of trance. I'm not sure if you were hallucinating, or blacked out, but you definitely weren't all there. And you've been losing a lot of time the last few days, right?" He nodded slowly, unsure of where she was headed. "Well, I think… you know how when I activate my powers, I switch personas? I think something similar might be happening to you."

His throat was suddenly very dry and his stomach twisted unpleasantly. "What do you mean? That I'm turning into him?"

He expected her to hastily deny it, offer some scientific explanation and reassure him. She didn't. Instead, she bit her lip.

"Not exactly. I don't have enough information yet to be sure, but I think something is triggering you into a split persona, like how I start acting like Killer Frost when I use my powers. It would explain the lost time, and why you've been aggressive towards me and Barry, and why you hurt Iris."

Cisco clasped his hands together tightly, like he could hold himself together with pressure alone. It would explain everything, she said. But would it? He had been conscious and aware when he hurt Iris- he had wanted to do it. Then again, he had been pretty deluded the last few days, so anything was possible, and it would certainly be easier on his conscience if it was an alternate personality taking over. Still, it didn't quite add up.

"It's just a hypothesis," Caitlin was saying. "Which is why I didn't tell you, because I didn't want to worry you or risk confirmation bias."

Then why tell me now? He wanted to say. What's another lie on top of all of the other's we've told? Instead, he clasped his hands tighter and blew out a deep exhale. "So where does Harry fit into all of this?"

"I called him for a second opinion, but I'm starting to think that was a mistake because he has so many opinions." She looked and sounded exasperated. "He wanted me to do an EEG while you were hallucinating so that we could see how your brain activity changed. That would tell us if you really were switching personalities. But I didn't want to do that without your permission. It felt…" She was playing with her hands again, intertwining her long, slender fingers and then pulling them apart. "…wrong."

He waited for her to go on, but she didn't. He let out another deep breath and turned to face her.

"I understand why you didn't tell me at first," he said slowly. "I know that the unstable-grieving-psycho-burnout thing I've had going on doesn't exactly inspire confidence. But, uh, I think if we've both learned anything from the last few days, it's that lying to each other doesn't get us anywhere. Can we both promise to be honest with each other going forward?" Her gaze dropped to the ground. He grabbed her hand and she looked up at him, startled. "Caitlin, please, this is important."

She took a short breath. "What if it's something that I really can't tell you? If I had told you this before, you would have reacted badly, which was why I didn't tell you. What if it's something like that?"

She had a point. What if she had told him while Reverb was still doing his creepy spirit guide thing? That would have been disastrous. He paused, considering it. "Then you can say, 'Cisco, there's something I can't tell you right now, but I will as soon as I can."

Her eyebrows shot up. "And you'd buy that?"

"Absolutely." Cisco nodded firmly. "Trust me, I know that telling the truth isn't always the best policy. I just need to know that I can trust you and that you trust me."

Caitlin bit her lip and then nodded. "Okay. But you have to promise me that you'll do the same thing."

"Okay." He breathed out an exhale. "I promise to tell you the truth, even if… even if it scares me." He swallowed, hard.

She smiled tentatively. "No more lies?"

He nodded. "I promise." He dropped his gaze to the ground. Did that apply to all of the things he still hadn't told her? It would probably do more harm than good to tell her about how much he'd enjoyed hurting people, and about his Vibe to the future, but how could he promise not to lie when he was still withholding the truth? He rested his head on one hand and closed his eyes. His migraine was returning.

"Hey." She squeezed his hand and he felt all of the nerve endings in his arm light up. He hadn't realized he was still holding her hand. "We're going to figure this out, okay? It's going to be fine."

"Yeah, I know," he said, but he didn't feel convinced.

Her eyes were searching his face again. He was starting to hate it. She could see through him so easily, and he hated that he was so transparent.

"You're exhausted," she said, and it was a statement, not a question.

"So are you," he pointed out. Her face looked pale and drawn under the dim fluorescent light, and the lines on her forehead were more pronounced than usual, like they'd permanently creased from her worrying so much. "You should go home and get some rest."

"I'm not going anywhere without you," she said firmly. "I don't want to leave you alone. If I'm right-"

"If you're right, you shouldn't be anywhere near me," he said, and he felt his face growing hot. He stepped back reflexively. "You haven't seen what Reverb can do-"

"You're not him." Caitlin stepped forward and reached for his hand, but he pulled it away. Her brow furrowed into a hard line with frustration. "This is why I didn't…" She trailed off and shook her head. "This is just a hypothesis, remember? Nothing's positive. I could be way off base about this. And even if I'm right about the split personality, that doesn't mean you're turning into Reverb. We can learn how to deal with this, just like I'm dealing with… her." Her eyes went unfocused for a moment and she shook her head again, as if trying to clear it. "It's been a long day, for both of us. Maybe we just need to get some rest and regroup in the morning."

"Yeah, I'm gonna sleep real well after finding out that I have my psycho doppelganger in my head." Cisco rested his head in his hands again, pressing his fingers against his aching temples. "If there's even a chance that you're right, I shouldn't be sleeping. Lowering my inhibitions is the last thing I should be doing."

"I'll get the spare cuffs, then," she said, as if it were the most obvious thing in the world. "You're already sleep-deprived. Besides the fact that I don't want you torturing yourself, we'll get the best results on brain scans tomorrow if you're well rested."

"Alright," he relented. "I can't promise that I'll actually sleep, though."

"That's okay." She reached out and touched his wrist lightly. He felt his breath catch in his throat, but didn't jerk it away. Her fingers still made his skin buzz with electricity, but her touch made him feel grounded and safe. "Let's get the cuffs and go."

He nodded and followed her out into the Cortex. He waited as she searched for the cuffs and gathered her briefcase and coat. She handed him the cuffs and they latched automatically around his wrists. Her eyes met his for a moment, and there was a flash of emotion that he couldn't place. If only he could read Caitlin as easily as she read him.

"Ready?" she asked, and he nodded again. "Good. Let's go home."

He didn't point out that she'd referred to his apartment as home.

It was after midnight when they got back to his apartment, and Caitlin looked even more exhausted than he felt, but she insisted on spending the night with him. She refused to leave him, even briefly, so he found a clean t-shirt and an old pair of sweatpants for her to borrow.

When she emerged from the bathroom, her clothes folded neatly in her arms, her hair was brushed smooth and her face clean. She looked even more tired without makeup on, but she still looked beautiful. Caitlin was just one of those people who glowed with natural beauty. She didn't need the makeup.

"Do you think you'll be able to sleep?" she asked. "I can stay up with you if you want. We can finish the documentary or watch something else or-"

"I'm fine," he interrupted, and she raised an eyebrow. "Okay, not fine, but I think I'll be able to sleep at least for a few hours. I promise I'll wake you up if anything freaky happens. You get some rest, okay?"

She nodded gratefully. "Okay. Good night, Cisco."

"Good night, Caitlin."

He pushed his bedroom door closed behind him, but not all the way. He didn't want to be completely cut off from Caitlin. He collapsed on top of his covered and burrowed his face into the pillows, feeling his head begin to throb again. He didn't tell Caitlin that his headache had returned because he didn't want any more drugs, and he didn't want her worrying any more than she already was. He was pretty sure that the headache was just a result of lack of sleep and the stress of the last few days.

Which brought him to the task at hand. He needed sleep and he needed it now, but closing his eyes somehow made them ache more, and he was afraid that if he fell asleep, Reverb or Thawne would creep back into his head. He rolled over onto his side and fumbled for his phone and earbuds on the side table. He searched through his iTunes for a few minutes before selecting the Light in the Piazza overture. Comforting, melodic white noise. He hit "repeat one", closed his eyes, and pressed his head down into the pillow.

He didn't sleep, but after a few minutes, his mind cleared and he felt his body relax. He could see all of the colors that lurked just out of the corner of his eye, dancing clear in the line of his vision. His headache melted away and his body felt weightless.

"In many ways, you have shown me what it is like to have a son."

Wells is standing in front of me, and his hand begins to vibrate as he raises it toward my chest. Except I know he's not Wells- he's Thawne. I've lived this before. I know how this goes.

I wait for his hand to sink into my chest, but it doesn't happen. Instead, I feel energy surge from my fingertips, and Thawne flies backwards. I have him pinned to the ground under a blue beam of light, and I can feel the vibrations of his body- the pulsating of his heart, the flow of his blood, the rise and fall of his lungs.

I can feel each one of his organs beating and vibrating and pulsing, and I could shatter each of them in an instant.

And I want to.

"Cisco," he gasps, his eyes wide, and suddenly, he looks nothing like I remember. He looks afraid. Terrified, even.

"Sorry, wish I could return the sentiment," I say. "But if you're a father to me, then you're a really crappy one."

My face burns with anger as I remember everything Thawne's done to me. Everything he's done to the people I love.

I feel a wave of energy pulsing through my arms and down to my fingertips, but this time, I'm controlling it. I can feel Thawne's heart beating even more frantically than before. The energy surges and releases in a huge sonic wave.

The vibrations of Thawne's heart screech to a standstill.

Cisco jerked upright and his earbuds dropped out of his ears. He could still hear the overture playing faintly on his earbuds.

That was… what was that? That was a dream, but it was vivid as hell. The worst part was, it didn't scare him. If he saw Thawne in front of him, he would rupture his heart in a moment. No, he wouldn't, he would slowly vibrate it with smaller sonic blasts, to cause the most suffering.

"Cisco?" He looked up to see Caitlin standing in the doorway. His t-shirt and sweatpants hung off of her slight body, but didn't completely dwarf her. Her hair was tousled and parted in the back, as if she'd slept with her head in one position for too long. Her appearance was sleep-tousled, but her eyes were too wide and alert for someone who had just been sleeping.

"Hey." He pressed the power button on his phone to check the time. 3:17 AM. "Did I wake you up? Was I screaming or something?"

She shook her head. "I just wake up sometimes. Why would you be screaming? Did you have another bad dream?"

"Uh-" he hesitated, and she raised her eyebrows, like she was daring him to lie after their pact. "Yeah."

"Do you want to talk about it?" He nodded. She stepped out of the doorway and sat on the edge of his bed, folding her slender legs into a cross-legged position.

"It was Thawne," he began, and he saw her shoulders tense at the name, though her face remained sleepy and impassive. "From the aborted timeline, when he-" He held a hand up, shaking it from side-to-side in a poor imitation of the freaky-ass hand of death. Only this time, he didn't kill me." He tried to swallow, but his throat was dry. "I killed him."

"It was just a dream," she said gently. "And besides, he wasn't a good guy, Cisco. In fact, he was sort of a piece of scum. And he hurt you in a lot of ways. All of us, but especially you."

"I know." Cisco ran his fingers through his hair. "That's the thing. I wanted to kill him. I enjoyed it." He clasped his hands together and brought them to his lap. "If… if he ever came back… if I saw him in front of me today… I think I would kill him. Or at least hurt him." He could see Caitlin's eyes widening, so he fixed his gaze on his fingers as he intertwined them. "I want him to feel even a fraction of the pain that he caused me. I want to make him pay for what he did."

Caitlin was quiet for a moment, and then said, "I know how you feel."

"You don't need to say stuff like that, Caitlin. It's enough for you to just listen."

"No, I mean, I feel the same way." His head snapped up and he looked at her sharply, but now she was fascinated with her own hands. "I would hurt Thawne too. And Zoom." Her hands clenched into fists, her knuckles white. "He tortured me. He made me doubt my own sanity, and everything I was. I want to make him suffer for that. Given the chance, I would put him through hell." She paused and squeezed her eyes shut, as if the very thought pained her. Cisco leaned forward and placed his hand on her knee, just to be touching her. "He constantly told me that he could see the darkness in me, that if I let it out, I could be a better version of myself. And I heard it so often that I believed it, but I don't think I needed that much convincing. I started to wonder, if I'm not a good person, then what am I?"

"You are a good person," he said in a low voice. She smiled ruefully.

"I'd like to think I didn't let the darkness win, but sometimes, I'm not so sure." She let out a shaky exhale. "I didn't know I could hate that much."

"Me either," he said quietly.

She nodded numbly, staring at her hands again. She looked so tired and defeated. He had only seen her like this a few times- without her pretenses to protect her. She rarely allowed herself to be vulnerable, even in front of him.

"You should go back to sleep," he said after a moment's pause.

"I don't know if I can." He raised his eyebrows, inviting her to elaborate. "I told you, I wake up sometimes. I'm not an insomniac or anything, I just-" she broke off. He waited for her to continue, but she was staring at her hands again. Her eyes were faraway and out-of-it.

"Cait," he said quietly, and when she didn't answer, he raised his voice. "Caitlin." She jumped and blinked quickly, like she'd spaced out. He wanted to ask her what was bothering her, why she hadn't been able to sleep, how long she'd been haunted by memories of Zoom like this. Instead, he just asked, "Are you up-to-date on Jane the Virgin?"

She looked up at him, taken slightly aback by the random question. "No, actually."

He swung his legs over the side of the bed. "Sounds like we have a date, then. You, me, and beautiful representation of the Latino culture."

She smiled and followed him out to the living room. He found the remote and settled onto the side of the couch. She sat down on the other side, and wrapped her arms around the pillow that she had been sleeping on. He turned the TV on and glanced over at Caitlin, her eyes still clouded with sleep and the corners of her mouth turned up with mild amusement at the punchlines. He had the strong feeling that he would do everything he could to protect her.

He noticed her eyelids slowly drooping, and then they fluttered open like she was trying to stay awake, but slowly closed again, and her head dropped to the arm of the couch. He reached for the remote and clicked the volume down so that the actors were reciting their lines in a low mumble.

I will never let anyone hurt you, he thought before he fell asleep.

"Cisco!" Caitlin sobs, and her eyes are wide, panic-stricken. "You need to leave, he's going to kill you-"

"Don't worry, Caitlin," a low voice says, and I spin around to see Zoom, grinning widely and malevolently. "Killing him would take all the fun out of it. Instead I'm going to make him watch you suffer."

His hand clenches on her upper arm and I see her flinch with fear and pain. Her pale arms are dotted with bruises, perfectly round bruises in sets of five.

His fingers.

His evil, dirty, fingers digging into her skin.

He doesn't deserve to touch her. He doesn't deserve her.

I feel my hands surge with energy and I'm stepping forward, no, flying forward, before he can hurt her anymore, before he makes her feel any less than he already has. I blast him out of the way, so that I won't hurt Caitlin, too, and then I have him frozen under my sonic boom. I can feel his organs vibrating and each one of his bones trembling.

I start by shattering his ribs, one by one.

An abrasive, screeching beep pounded against his skull. Cisco groaned and opened his eyes and realized that Caitlin was curled up against him. Her head was resting on his thigh and the rest of her body was folded up on the other half of the couch.

She looked so peaceful that he didn't want to disturb her, but the screech was grating against his head and shredding his nerves. His sleep-fogged mind tried to identify the source of the noise, but he was too tired. His eyes were seared by the dim light of the sun seeping in through the window blinds- it was morning. He realized that the intrusive beeping was Caitlin's phone, vibrating against the glass coffee table. He leaned forward, trying to reach it without moving, but it was several inches out of his reach. He scooted forward slightly and he felt Caitlin stir. Damn. He picked up the phone and read the name on the screen- Barry Allen. Caitlin's head had flopped over to the other side of the couch, but she was still asleep, so he slid his finger across the screen to answer the phone.

"Barry?" he asked, his voice croaking with sleep.

"Cisco?" Barry sounded surprised to hear him. "Where's Caitlin?"

"Asleep. She spent the night at my place." He crossed his arms, even though Barry couldn't see him, remembering that he hadn't seen Barry since before he broke Iris's wrist. That would be a fun conversation.

"She spent the night with you?" Barry asked, shocked, and Cisco realized his mistake in phrasing.

"I didn't mean like- it's not important. What do you need?"

"I was calling to see if she was coming in," Barry said. "We, uh, have a situation."

"What is it?" He sat up straight and jolted the couch slightly. Caitlin groaned softly and stirred again.

"Uh," Barry said. "Harry's here." Cisco felt his heart rate jump a little. "And he wants to talk to Caitlin, and he seems kinda pissed. When she's awake, can you tell her to come in as soon as she can?"

"Yeah, she's waking up now. I'll send her over soon." He hung up and placed the phone on the coffee table. Caitlin was sitting up, not yet fully awake.

"Who was that?" she asked blearily.

"Barry." He combed his hair behind his ear. "And, uh, Harry's here."

Caitlin's eyes widened. "What? I told him not to-" she scrambled to her feet, wobbling slightly on her tired legs. "What time is it?"

"It's-" He bent down and clicked her phone on. "7:41."

"I'm surprised Barry's there that early," she muttered, and picked up her folded clothes from last night, which were sitting on the coffee table. "I need to go talk to him." She turned and started towards the bathroom door.

"Hey, easy," he said. "You just woke up." And she had been sleeping next to him. He couldn't help but feel slightly heartbroken that their night together, strange and tiring as it was, was over and she was rushing off.

"I can't sleep all day," she said briskly. "And I want to give Harry a piece of my mind. I told him not to come here unless I told him to, and of course he didn't listen to me…" She shook her head. "You can stay here if you want."

"No." He shook his head. "I don't want to stay here and just… wallow. I need to do something."

She nodded. "Get ready, then. We'll leave in ten minutes."