"I hate this." Cisco mumbles.

Caitlin turns to look at him and sees him mindlessly tapping away on the keyboard.

"Cisco if you keep that up you might accidentally screw up the calculations." She reaches over and pulls his hand away from the keys.

"That'd be a real shame wouldn't it. We'd have to run them again. Postpone this whole thing. Maybe even forget it completely."

"Cisco..." Caitlin says, turning in her chair to face him. "I hate this too." She says softly.

"Then why are you going along with it?" He asks, half-scolding.

"Because...it's not my choice. Ultimately, it's Barry's. And the only way he can feel confident in whatever choice he makes is if all the variables are already laid out when he makes it."

"Okay, and what about the variable of all of our lives changing and us not remembering it and you and I never meeting him?" Cisco rambles out.

"He knows that."

"He's family, Caitlin. And we're gonna lose him." Cisco looks down at his hands that are clasped together in his lap.

"We won't remember that we lost him. And it's us or his mom. Which would you choose?" She asks, sticking her head up under his to make him look at her.

"I wouldn't want to choose." He whispers.

"Neither would I." She says, smiling weakly at him. "So, all we can do is support him."

"You get someone back too." Cisco points out. "Do you want him to go back?"

"I...I don't...no. No, I don't. I made peace with my father's death a long time ago. I miss him every single day, but he's gone, and I know he'd be proud of who I am and what I've done. I like my life. With you. With Barry. I'm not ready to give that up."

"Then tell him that." Cisco begs in a whisper.

"I can't make the decision for him Cisco. And my dad died in a car crash. It was much easier to make peace. Barry's mom was murdered. He spent his whole life chasing that. And now it's here. He will either make peace with it now, or he'll go back. We can't take that from him. We just have to trust that he'll make the decision that's best for all of us. Whatever that is."

"I don't want to lose him." Cisco says looking up at Caitlin. "I don't want to lose you."

Caitlin smiles back at him. "We're family Cisco. It's been you and me through all of this. We'll find each other. I know we will."

"Any universe?" He asks with a child-like pleading look on his face.

"Every universe." She says, pulling him in for a hug.

He hugs her back and buries his head in her shoulder. She can hear him sniffling and she holds back a laugh at how young he seems right now. She feels him reaching for the desk and turns to see him pushing their chairs away from the desk.

"What are you doing?" She asks.

"Rolling away."

"From?" She asks, amused.

"The calculations are done. I don't want to see them." He admits, pulling away from her.

She laughs and turns to see the screen. "Damn." She says under her breath.

"What is it?" Cisco asks, wheeling up next to her.

"Barry's speed. To open the portal, he'll need to go faster than he's ever gone."

"How fast?" Cisco leans into the screen. "Oh...that's fast."

***************************************

"What's the news guys?" Barry walks into the cortex with Joe to find Caitlin and Cisco explaining what they've found to Professor Stein. They all stop talking and turn to him. "I take it it's not good news."

"We talked to Thawne. I talked to Thawne. That splat I was telling you about earlier? Yeah. His plan is to have you collide with the hydrogen particle in the accelerator." Cisco explains, spinning slowly in his chair.

"Once you collide, a portal will open." Caitlin starts.

Joe narrows his eyes. "A portal?"

"A time...portal." Caitlin says, widening her eyes and raising her eyebrows in disbelief that she's pretending to know anything about this topic.

"At which point I plan on shouting something like 'Eureka!' or "Excelsior!'" Stein says. "I'm uncommitted.

"Great so what's the problem?" Barry asks.

"If you're not running fast enough when you collide with that particle..." Caitlin says.

"Splat." Cisco jumps in.

"How fast?" Barry asks.

"Mach Two. At a minimum." Caitlin answers. "Barry, you've never gone that fast."

"Yeah I have." He defends. They all raise their eyebrows at him. "When I traveled back in time the first time. When I was running to stop the tidal wave. Caitlin had just said that I reached Mach Two."

Caitlin and Cisco look at each other. "You haven't run that fast since." Cisco says hesitantly.

"Mr. Allen, if I may." Stein steps into the middle of the room to get attention. "If you were in fact running to stop a tidal wave, your body was flooded with adrenaline and a combination of emotions that will be difficult to replicate."

Barry sighs. "So, what? We have to try. Just tell me it can work." He turns to Cisco with a pleading look on his face.

"I mean on the one hand it makes a kind of sense. On the other...why? Why would you even consider doing this?"

"You know why."

Cisco sighs. "Let us run some more calculations to make sure we've covered our grounds. We still have that whole wormhole thing to sort out."

Barry nods. Cisco abruptly stands from his chair and walks out of the room. Barry turns to Caitlin who nods and motions her head toward to door. Barry follows Cisco out.

"What was that about?" Joe asks Caitlin.

"He's not completely on board with all of this." She admits.

"His reason being?" Joe asks.

"Aside from all the risks?" Caitlin starts. "Barry is his best friend. As much as he'd love to see him be able to save him mom, the idea of losing him, either to something going wrong or to a change in the timeline, isn't exactly sitting well with him." She says, looking down. "With either of us." She mumbles, thinking no one can hear her. Stein turns to her when she says it but says nothing.

"We'll get started on the calculations, Detective." Stein says. "We'll be sure to alert the team when they are finished."

Joe nods and leaves. Caitlin stands and walks over to the control desk.

"I wish this was more of a 'will there be a worm hole' question and less of a 'how big will the worm hole be' question." She says, smiling weakly at Stein.

Stein and Caitlin get down to business first, discussing all the different variables they'll need to account for. Time in the worm hole, atmosphere, etc. Once all the variables are in, they just have to wait.

"You have a unique position in this Dr. Snow." Stein starts.

"Please, Professor, you can call me Caitlin." She says, smiling up at him. "I don't really have a position in this at all, really. Just a bystander with a little more knowledge of the situation than she'd like."

"A bystander who will gain and lose something no matter what choice Mr. Allen makes." He corrects. "Have you discussed the decision with him?"

"Yeah. A little. I don't want to sway his decision, so I'm trying to avoid the conversation."

"Is there something in particular you're scared you might say that would persuade him?" Stein asks.

Caitlin looks up at him, confused. "I'm not even sure what I want him to choose. Not sure what I could say then to influence him."

"On the contrary my dear, I think you know exactly what you'd choose." She looks away and to the computer screens. "You want him to stay."

She stares at the screens, her breathing picking up. "I just don't think I personally could choose to go back. Too many things that could go wrong."

"Too many people you might lose." Stein adds. "I think he is realizing that himself. Thus, why he hasn't quite made his decision yet."

"I suppose." Caitlin responds.

"People like Mr. Ramon." Stein says, eyeing her. Waiting for her to see where he's going with this. "People like you. He may never meet you or Mr. Ramon in this new timeline. You two may never work at S.T.A.R. Labs or even in Central City."

"Maybe. Who knows what will happen?" Caitlin says blankly.

"However, if he should stay...he would continue being the Flash. Saving people. Mr. Ramon and yourself by his side. Who knows where that will lead all of you, but no one could doubt that it will be an interesting and rewarding life."

"You're preaching to the choir here, Professor." Caitlin says, chuckling.

"Does he know fully the life he could have if he stays. What is here for him?" Stein asks.

"I'm not sure what you mean."

"Is Mr. Allen aware of the depth of your feelings toward him." Stein asks, accusingly.

Caitlin quickly turns to face him. "That shouldn't matter."

"But it should, Dr. Snow," he starts. "Caitlin, I'm sorry. It should. I heard you speaking to Mr. Ramon earlier. You want him to be aware of all the variables. Is your affection for him not a variable?"

"Not an important one." She defends.

"I would argue that it is the most important one." Stein sits and scoots closer to Caitlin. "Love...love would be enough to make him stay."

"I never said I loved him." Caitlin defends.

"When it is as clear as yours is, my dear, saying it is not necessary." Caitlin turns to see Stein smiling at her.

"I don't want him to stay for me. If he chooses to stay, it needs to be his choice, fully his choice. Or I'm scared he'll question it someday. Regret it even. My feelings should not be factored into this because...because if he chooses to go then I won't even remember that I felt that way."

"And then he would never know. Wouldn't that be the greatest tragedy of all?" Stein recites.

"When did you become such a romantic?" Caitlin asks. "I thought scientists were supposed to be realists?"

"On the contrary!" Stein exclaims. "Even Einstein was known for his words on love. He himself said 'any man who can drive safely while with a pretty girl is simply not giving the girl the attention she deserves.'" He smiles at this.

"Yet if he gives her his attention, the car will crash." Caitlin argues.

"You are quite the realist, aren't you?" Stein says, smirking at her.

"Side effects of being raised by a psychopathic murderer." She says, half-jokingly.

The computer starts beeping and they both turn to look at the screen.

"Oh dear." Stein says rubbing the back of his neck.

Caitlin leans over to press the button for the intercoms. "Barry. Cisco. We need you in the cortex."

Seconds later Cisco is set down in the middle of the cortex, bracing himself, and Barry is looking at Caitlin.

"What'd you find?" He asks.

"The worm hole," Stein starts. "We can keep it under control, but only for so long. If you stay beyond the given time, we risk a global catastrophe."

"How long do I have?" He asks, turning to Caitlin.

"One minute and fifty-two seconds." She says, looking back at him.

"That's...not very long." Cisco interjects.

"That gives me enough time to save my mom, but not enough time to get back and stop him."

"I'm sure he's aware of the limitations the time puts on you." Stein says.

"That's it Barry. That's all you need to know." Caitlin says.

"It's up to you now." Stein finishes.

Stein and Cisco leave the room, noticing Barry's eyes not leaving Caitlin who is working on the computers.

"You said I would know what to do?" He starts.

"Do you not know, or do you not want to say it?" She asks, leaning forward on the desk and crossing her arms.

Barry takes a deep breath.

"You said you want someone to tell you what to do." She says. He nods. "The way Joe made it sound, someone already has."

Barry looks at her confused.

"Your dad. You went and saw him this morning, didn't you?" He nods. "What did he say?"

"My mom wouldn't want me to save her." He says, sounding defeated.

"Do you believe that?" Caitlin asks softly.

"I don't know." He admits. "I want to believe that she'd want me to save her, but at the same time..." He takes a deep breath. "I want to believe that she'd understand if I don't. She'd want me to live my life."

Caitlin doesn't say anything. She sits and lets Barry think for a minute. He looks up at her.

"What don't you want to say?" She asks.

His face is worried. Hesitant. She gives him a light, but genuine smile. His face becomes blank. He stands up and heads to the exit. "I gotta talk to Joe." He walks out without another look to Caitlin.

Cisco peeks his head from around the corner. "What was that about?" He asks.

"Assuming you were listening the whole time? You know as much as I do." She says, looking worriedly at the exit.

"Well what does he need to talk to Joe about?"

Caitlin leans back in her chair. "I think he's made his decision."

*****************************

"Tell me the easy way isn't the wrong way." Barry tells Joe.

"What do you mean, Bar?" Joe asks. He's standing in the door frame to Barry's lab watching him pace.

"I mean...Joe you told me what to do the second I told you what Thawne offered. I could've turned around right there and done it. No questions asked. But I didn't because something was holding me back. My dad told me not to and I could've turned around and decided to stay, and at first, I thought the reason I hesitated was because I felt guilty. But you were right. My dad was right. She would want me to be happy. She would want me to live my life. She'd be proud of me."

Joe is watching Barry with wide eyes as he rambles, practically talking to himself, and continuing to pace.

"Staying is easy. Staying means nothing changes. It means finally catching the man that murdered my mom and making him pay. I get everything I've ever wanted if I stay." Barry starts. "But going back gives me something I never thought I'd get to have."

"So, what's your decision Bar?" Joe asks. He walks up and puts a firm hand on Barry's shoulder.

Barry turns to him and gives him a weak smile. "I love my family, Joe."

****************************

Barry and Joe walk into the cortex. Stein, Cisco, and Caitlin are sitting and waiting to hear what they called them here for.

"I don't mean to complain, but you told us to be here at 1:30. It is late. I am tired. I need my beauty sleep." Cisco complains.

"What Cisco means to say," Caitlin starts. "Is how in the world is a speedster always late? We've been here almost twenty minutes."

"Have you made your decision, Mr. Allen?" Stein asks, pulling everyone's attention back to the topic at hand.

"I have." Barry says, looking at Joe who gives him an encouraging nod.

"Are we going back, or are we going forward?" Stein asks.

Barry turns to look at Cisco and Caitlin. Both of them have nervous looks on their faces. Stein can barely contain his excitement. Joe is staring at him, waiting for him to speak.

***

"So, what's your decision Bar?" Joe asks. He walks up and puts a firm hand on Barry's shoulder.

Barry turns to him and gives him a weak smile. "I love my family, Joe."

Joe sighs and pulls Barry in for a hug to hide the look on his own face. He had to be supportive, even if every ounce of him wanted Barry to stay.

Barry takes a deep breath and hugs Joe back. "So, I'm gonna get my dad out of prison. And finally put away the man who murdered my mom."

Joe pulls back, a look of pleasant surprise on his face. Barry smiles back at him.

"You're sure?" Joe asks.

"I'm sure."

"Then let's go get that bastard."

***

"Iron Heights will have to make some serious accommodations to start boarding metas, especially Thawne, before we can move them. We'll have to find a way to get a confession. I don't think he'll do it willingly. We'll have to move quick, I'm not sure that cell will hold him long." Barry rambles.

Cisco stands up and walks over to Barry, not saying a word. Barry stops talking and looks at him, smirking. Cisco aggressively hugs Barry and buries his face in his chest.

"Think you can help with Iron heights?" Barry asks Cisco as he pulls away.

"It would be my pleasure." Cisco says, bowing in front of him. He excitedly runs off to his workshop.

"Moving forward I see." Stein says, smiling at Barry. Barry smiles back at him and nods. "Then I will be taking my leave." Stein walks over to Caitlin who stands to give him a hug. He leans close enough to whisper in her ear without the other two hearing. "I believe he has just parked the car." Caitlin pulls back and gives Stein a nervous smile.

Joe follows Stein out of the cortex. Barry slowly makes his way over to Caitlin.

"There's a new Thai place downtown." Barry says, a smirk forming on his face. "Opening night is next Tuesday. I thought,"

He is cut off by her pulling his face to hers, their lips meeting firmly. She moves her hands to back of his head and into his hair, his hands wrapping around her and pulling her closer. He moves into the kiss for only a second before she pulls away, breathing heavily.

She looks up at him, eyes glistening with tears, and doing a poor job of hiding the smile that's threatening to break out on her face. "I love you." She whispers, only audible to him.

Barry smiles and lets out a laugh. He presses his forehead against hers in relief. "I love you too."

They stand there with their foreheads pressed together and arms around each other for a few seconds, catching their breath, before Barry breaks the silence.

"So, Tuesday?"

Caitlin laughs and drops her head to his shoulder. "Tuesday sounds great."

At the entrance to the cortex, Joe and Stein are peeking around the door frame. They both step back and smile proudly at each other before starting their walk to the elevators.

Stein turns to Joe as the elevator doors close on them, his pointer finger in the air, and a proud smile still on his face. "Excelsior!"