"Whoa, careful there. What exactly do you think you're doing?"

Lexa grunted as she gave one last tug to break the branch free. "Ha! This is perfect!"

"For... your walking stick?"

Lexa rolled her eyes as she swung one end of the branch into Clarke's shoulder.

"Hey now," Clarke said in mock offense as she rubbed her arm. "You're gonna knock me out of this tree, and not only would that be a forty-foot fall, but I'd be quick grub for walkers."

"They wouldn't touch you now that I have my new weapon here." She grinned. "This branch is the perfect thickness to use as a bo staff. I can't just wait up here, hoping they'll leave soon, Clarke. We need to fight our way out, and you need to take me to the Flame."

Clarke frowned. "What about your family? We're about halfway through the forest now, so it will take us just as long to either find them or go back to Polis."

"I desperately want to find them, Clarke, and I can't imagine what they must be thinking with me gone, but..." She sighed. "Again, I don't know quite how to explain it. I just need to find the Flame. Besides, how would we make sense of all this to them? If we go to them first, we'll have to explain why it's so urgent that we go back through a zombie-infested forest to find the ruins of a city only we remember as Polis. How do we do that?"

Clarke shook her head. "I don't know. I just want to make sure you're fully okay with this first. I know how much they mean to you."

Lexa placed a hand on her shoulder. "I know, and thank you. But if the Flame really is going to help us like I think it is, then us finding it as soon as possible can only help them too."

Clarke nodded. "As you wish, Commander." She looked down at the walkers who were ambling aimlessly below them. "Well, I'm not gonna use my gun in case the sound just attracts more of them, and I'll have to be pretty close to use my knife, so I think I'll need to find me a bo staff as well."

"Hold up. I've got you." Lexa stepped gingerly over branches to the other side of the thick tree. "Here we go," she muttered, followed by a loud crack. She came back around and smiled proudly as she sat down on her branch next to Clarke. She spent the next minute stripping off the extra branches sprouting off of it and handed the finished product to her companion.

"What do you think?"

"It's perfect!" Clarke smiled as she spun it around, testing the weight in her hands. "We are about to make some heads roll!"

Lexa shuddered. "I can definitely stomach all this better now, but it's still absolutely disgusting."

"Yeah, it is." Clarke glanced down to the ground. "Looks like there are about twenty-one. How about this - let's try to find a low-hanging branch and see if we can crack a few skulls from there first without having to hit the ground. That will save us a little trouble."

Lexa nodded. "Good idea. Shall we?"

"Let's do this."

Clarke's idea worked quite well - they were able to take out thirteen walkers who wandered too close to their branch in search of brains. When the girls dropped to the ground they only had to handle a few kills each to clear their path.

"Well done, beautiful." Clarke smiled as she leaned in to give her a soft kiss. Lexa let out a moan in pleasure but then stepped back. "Don't go getting me turned on again right now." She warned with a smirk. "We need all this adrenaline for staying alive."

Clarke's head fell back as she laughed. "Fair enough." She winked as she slipped her hand into Lexa's. "Let's go."

Two hours and eleven zombie skulls later and the girls were back in Polis.

Lexa took a deep breath. "Okay. Where to?"

Clarke used her staff to point straight ahead. "There."

"The tower?"

Clarke nodded. "Yep. I'll show you. Just pray the Flame's still where I put it."

Once they stepped into the ruins of what had once been a grand entry room, Clarke moved automatically toward the other end and knelt down. She immediately found the stone she was looking for in the floor and scraped away around its edge until it loosened. She looked around the room. "Hey, can you bring me that flat stone right there?" She pointed at the object in question and Lexa brought it to her. "Thanks."

Lexa watched her curiously as she worked. Clarke pried up the stone in the floor and used the one Lexa had brought her as a little shovel. She dug for several minutes going nearly a foot deep when she heard the stone strike something hard.

"Yes! This is it!" Clarke reached into her hole and felt around for the metal handle. She grasped it and pulled as hard as she could, but the box hardly budged. She moved it back and forth to help loosen the packed dirt that encased it. She fell back as it finally pulled free and clutched it close.

"This is absolutely incredible," Lexa marvelled as she stared at the small metal box. "This actually is all real, isn't it?"

Clarke loved the look of wonder in her eyes and smiled. "Yes, it is." She set the box down in front of her. "The latches are rusted shut," she muttered. She grabbed her stone trowel and banged against the fixtures several times until they shattered and the box opened.

Lexa gasped and knelt down next to Clarke as she carefully pulled out the shredded remains of the first Commander's spacesuit. Clarke folded back the fabric to reveal the old journal and the container with a skull on the front. "This is it," she whispered as she slid back the panel. Clarke grinned as she delicately removed the Flame from its cushion.

Lexa admired it reverently, then looked to her partner. "I know what we need to do now, Clarke. You need to implant the Flame back into me."

Clarke stared at her. "You can't be serious. I can't even count all the issues I have with that idea."

Lexa just smirked and folded her arms. "Try me."

"Okay, well, for one, I may have been a doctor in my past life, but I haven't ever touched a scalpel in this one. Plus, who knows if that thing is even sterile."

"Your body now may not be conditioned the same as it was then, and you don't have the exact same muscle memory, but if my hands remember how to throw a spear and use a bo staff, yours can wield a scalpel again."

"Okay, fair enough. Let's hope so. Next issue: You aren't a Natblida anymore."

"But I was once."

"But not in this body. Not in this lifetime."

Lexa shrugged. "It doesn't matter."

"Doesn't matter?" Clarke laughed incredulously. "You do know that anyone without the Nightblood is killed by the Flame, right?"

"But I did have it, Clarke." Lexa tilted her head and stared at Clarke intently. "Clarke, what happened to the last Nightblood vials."

Clarke gulped. "Why?"

"Because they were intentionally left unused to fulfil a specific purpose that was never revealed to me or the past Commanders. Did Luna know what they were for?"

"Yes."

"Well?"

Clarke looked away. "They, uh... She said they were for me."

"Ha!" Lexa exclaimed. "I knew it! Tell me why."

Clarke shrugged. "That's just it. I don't know why."

Lexa grinned. "So you were a Natblida too."

"Yeah, but for what purpose? The spirit of the Commanders was never meant to reside within me."

Lexa's brow furrowed and Clarke could see the gears spinning in her mind.

"You're right - I don't think it was meant to be put in you, but to be used through you."

Clarke arched an eyebrow. "Say what?"

Lexa's voice rose in excitement as she started theorizing. "There's some reason we both needed the Nightblood in our veins, Clarke. It forged some kind of connection between us - even if we don't have it now - but I think the only way I'll fully understand is when I have the Commander's spirit in me again. Then it can communicate with me directly."

"It was gene therapy," Clarke whispered.

"What was?"

"The black Nightblood serum. Once I read everything in Becca's journal I understood it better. When she first returned to earth she injected the people she found with the gene therapy, but she didn't use it all. It takes several doses over a period of time to complete the process, and that's what enables the AI to successfully interface with its hosts. Otherwise they die. But with it, you have access to the consciousness - the memories of everyone who had interacted with the Flame before you. It's an unparalleled feat of engineering. Absolutely incredible."

Lexa nodded. "It really is. I still can't believe I had that in me." She took a deep breath. " And now I need you to put it back."

Clarke shook her head. "I really don't feel comfortable with this, Lex. Something could go terribly wrong. I can't risk losing you for this hunch."

"It's more than a hunch, Clarke."

"Whatever it is, it could kill you. You can't deny that. Life right now might feel like a living hell, but it's better than death."

"But I may not die."

"You don't know that."

"I kind of do."

"But how?"

"Clarke!" she groaned in agitation. "We don't have time for this! Just put the blasted thing back in me!"

"I can't lose you again, damn it!" Clarke's lips quivered and a solitary tear streaked down her face.

"Oh, babe." Lexa's face immediately softened as she wiped the tear away. She kissed her cheek and rested her forehead on Clarke's. "I know - I know how this idea must sound and how you must feel, but trust me. This is something I feel deeper than anything except how much I love you. This is going to work."

Clarke sighed in submission. "Okay," she whispered. "I do trust you."

"Thank you." Lexa looked at the Flame and smiled. "The sacred symbol. Little did I know then that it was actually the infinity symbol."

Clarke chuckled. "That reminds me - I need to brush up on my Latin." She carefully picked up the journal and started flipping through the pages.

"Latin?"

"Yes. There's a Latin phrase that's used to activate the AI and one to deactivate it. Ah, here we go." She pointed out the location in the book. "Ascende superius. It means 'seek higher things' - the motto of Becca's scientific corporation."

The AI immediately sprang to life with dozens of tiny tendrils spreading out from its core. Both girls gasped.

"Well, I'm glad it still works!" Clarke laughed and looked back at the journal. "And now to deactivate it... Ah, yes. Quia nunc vale."

The Flame's tendrils retracted and Clarke placed it back in the case.

"And what does that phrase mean?"

"Goodbye for now."

Lexa stared at the Flame in wonder. "Wow. It's amazing how much I didn't know about the thing that lived in my head for years."

"And how much our old selves have been part of our current selves. We really aren't all that different from who we were then, are we?"

Lexa shook her head. "Not much. I mean, of course we're influenced by our environments and responsibilities, but in essence we're the same."

"Different lives, same souls."

Lexa smiled and leaned in to kiss her. Clarke set the Flame down and wrapped her arms around Lexa's neck, deepening the kiss.

"I can't lose you," Clarke whispered.

"You won't."

"I just barely found you."

"I know. But you trust me."

"I do."

"Good," Lexa responded as she pulled back. "So, what do we need to do?"

Clarke reached for her knapsack. "Well, we'll use Becca's scalpel. It's better to use for such a precise cut than my knife would be. I have some matches here I'll use to sterilize it, then I have a needle and nylon thread that I'll use to stitch you up."

Lexa laughed. "How in the world do you happen to have a needle and thread?"

Clarke lit a match and held it under the blade. "From the group I used to be with. A man with us was a doctor."

"Oh." Lexa knew everyone who had been in that group had died. "I'm sorry."

Clarke cut a strand of thread and placed it through the needle. "Don't be. I hardly knew them myself." Clarke cleared her throat. "Okay, take this cloth and bite down on it as hard as you have to once I start. It's better than biting your tongue or cheek. And hold onto something - maybe your staff. This is going to hurt."

Lexa nodded. "I know. So, you'll make the cut, activate the AI, put it in, and then stitch me back up?"

"Yep. That's it. Shouldn't take more than a few minutes."

"And you've done it once before. On Luna."

"In my past life, yes." Clarke chuckled. "So I'm basically a pro."

Lexa smiled. "Perfect. That's all I need to know."

Clarke took a deep breath. "Okay, let's do this. Lie facedown and tell me when you're ready."

Lexa stretched out on the ground and grasped her staff. "Ready." She stuffed the rag in her mouth and clamped down.

Clarke took the sterilized scalpel in her left hand, brought the Flame close, and braced herself.

"Okay," she whispered. "I'm going to make the cut now." She willed her hand to stay steady as she made the short incision. The rag under Lexa's neck immediately started collecting blood and Clarke winced at the pained groan she heard coming from the woman she loved. She quickly but carefully picked up the AI.

"Ascende superius."

The Flame activated and Clarke used her fingers to splay the split skin ever so slightly as she inserted the AI. The Flame immediately took over - its mechanical tendrils knowing exactly what to do as they latched onto the inside of Lexa. Clarke used another cloth to dab at the pooling blood and pinched the skin back together as she picked up the needle. She took another deep breath and skillfully wove the needle in and out of the skin of her neck.

Clarke had held her breath for nearly a minute and finally let it out as she finished the last stitch. She quickly cleaned up some of the residual blood and wrapped a bandage several times around Lexa's neck.

"I'm done," she whispered.

"It's about bloody time!" Lexa growled. "I don't think I've ever been in that much pain in my life!"

Clarke cringed. "I'm so sorry, babe. I tried to do it as fast as possible."

"I know. It's just that... Whoa." Lexa started sitting up and Clarke immediately pinned her back down.

"What the hell, Lexa? You can't get up quite yet! Just relax." Clarke was stunned when she heard her laugh.

"Sorry! But, Clarke, this is amazing. I don't feel the pain anymore!"

Clarke froze in terror. "Oh, god. Lexa, I don't think that's a good thing. That's exactly what happened when ALIE hijacked a person's mind."

Lexa propped herself up slightly on her elbow so she could look at Clarke better. "But this isn't ALIE. This is version two."

"But it didn't eliminate your pain before!"

"It did, though, Clarke. I had just forgotten."

"What do you mean?"

"The first time I had the Flame put in - my Ascension Day. It was just like this. Titus had given me medicine that would help with the pain, but then soon after I had the spirit of the Commander within me, the pain subsided just like this."

"But you never lost that memory? Or other painful memories?"

"Heavens, no. I remembered them all as clear as the day they happened - perhaps even more clearly than other people remember their past."

"That's incredible. Maybe this actually is going to work."

Lexa nodded, then was silent for a moment and looked deep in thought.

"What is it?" Clarke questioned.

"You were so good with Luna." A slow smile came over Lexa's face and she tapped her head. "I have her memories now, and I see how much you helped her on her path to Ascension. You are a remarkable person, Clarke Griffin. Then and now."

Clarke laughed. "Well, thank you, but I have to say I'm just a little creeped out by the fact that you have access to the memories of all the previous Commanders."

Lexa shrugged. "You get used to it. Everyone gets very comfortable with each other."

Clarke's brow furrowed in concentration. "So, what happens next? Have you learned anything more from the Flame about what we need to do?"

Lexa nodded. "I think so. Give me a couple minutes. This is a lot for me to process."

"Yeah, of course. I'll clean all this stuff up and then you can tell me what you know."

Lexa just nodded as she slowly sat up and moved to another part of the room.

Clarke worked in silence as she cleaned the scalpel and needle and gathered up the bloody rags. She hoped Lexa wouldn't need too much processing time because the anticipation was killing her.

It was about five minutes before Lexa spoke again. "Clarke."

Clarke hurried over and sat cross-legged facing Lexa. "What is it? What did you find out?"

Lexa's eyes widened. "A lot. It's a bit overwhelming."

Clarke stayed silent, waiting for her to continue.

Lexa looked straight into her eyes. "Clarke, we're going back."

The blonde's brow furrowed. "Back where?"

"Back in time. Clarke, we're going back to our old lives!"

"What are you talking about? That isn't possible."

"It's the Flame, Clarke. It's going to take us back." Lexa was trying to stay calm, but Clarke could see the excitement rising in her.

"This doesn't make any sense, Lex! Please just explain what you're telling me so I can stop trying to ask questions."

Lexa nodded with a smile. "The Flame has complete access to my consciousness, right? Well, time is a funny thing, Clarke, and The Flame doesn't perceive time the same way we do."

Clarke brought her hands up to massage her temples. "When I said to explain I meant in English, please."

"Okay, I'm saying the Flame has access to my consciousness from any point in my existence - this life or the last - and it can reawaken that consciousness, in a sense, and send me back to that point."

"So, kind of like a checkpoint in a video game?" Clarke suggested. "You die, but you don't have to start all the way back at the beginning of the game - you just start over from the checkpoint."

"Yes, exactly! So, just like in a game, when you go back to that checkpoint, the rest of the game isn't set in stone. You aren't destined to repeat the exact same fate if you don't make the same decisions."

Clarke paused for a moment, processing what she was hearing. "So only you will go back?"

"No, Clarke. We both will."

"But you're the only one with the AI."

Lexa smiled. "But this is why Luna had you take the Nightblood - the gene therapy. Even though only the person with version two implanted in them has access to the memories, the Flame has access to the minds of all Nightbloods. They are part of the neural network even though they don't realize it. But I didn't know this before - it wasn't like I could see into the minds of my Nightbloods, but the spirit of the Commanders can. It knows each of us before we even ascend."

Clarke gasped. "So the Flame had access to my mind as soon as I took the gene therapy and became a Nightblood."

Lexa grinned. "Exactly."

"So it can take me back too?"

"Yes. It's not that the Flame is only able to work through me, it just needs a living host for it to be activated. But it has access to both of our streams of consciousness."

"So has this been done before? Has the Flame taken another Commander back in time?"

Lexa shook her head. "No, otherwise I would have their memories of an alternate timeline."

"So I won't be a Nightblood when we go back?"

"Not if we go back to a time before you injected yourself, which is what I would prefer, since I'd like to be alive."

Clarke chuckled. "Obviously. So at what point is the Flame going to take us back?"

"That's up to us, actually."

"Seriously? Why? Can't it calculate the perfect point for us to return to so we can fix things?"

"I'm sure it could calculate some of the most opportune times for us to go back, but it can't determine the future for sure, and once we go back in time, the future will no longer set in stone. Besides, version two is programmed to preserve humanity's agency, which is what ALIE stripped from people, and that's why it's having us choose when to go back. It's all about choice and free will. What we need to do is stop ALIE, and we now know everything we need to know. Plus, you've already stopped her once."

Clarke nodded. "Yes, I have. So we keep all our memories, right? Otherwise this would all be for nothing..."

"Yes, we will remember all of this. It will be as though the Flame is taking this current consciousness and embedding it into a prior point. Imagine that video game analogy again and you get these awesome upgrades before you die, and then you get to keep the upgrades when you start over at the checkpoint."

"Okay, okay. That actually makes sense."

Lexa laughed. "Good. Now you see why I needed that time alone to process."

"Yeah, but you only needed like five minutes! You must be a genius."

"Well, I was a straight-A student with a full-ride scholarship..."

"Alright, don't go getting cocky now."

Lexa winked. "You know I'm just teasing you. Plus, having the AI actually inside my head to feed me all this information is so much easier than me trying to explain it, so you're definitely a genius yourself for even comprehending what I'm telling you."

"I guess that makes us pretty evenly matched."

Lexa grinned. "Yes, it does."

Clarke's expression turned serious. "So, I guess there's just one thing left for us to decide."

Lexa nodded. "To what point in time do we go back?"

Author's Note: Guys, I had so much fun writing this chapter! Now, I'm sorry this note is so long. The next three paragraphs are just me geeking out over Latin and explaining why I'm quite sure the phrases and meanings I used in this chapter are accurate. So, if you don't care about all that, just check out the last paragraph. Or don't read any of it! Haha. Otherwise, join me, fellow nerds...

Let's talk Latin. In episode 3x07 (Thirteen) both Becca and Titus say something to the Flame that deactivates it, and I read a lot of discussion about the exact phrase and meaning. (Yes, I am that nerdy.) The writer of the episode, Javier Grillo-Marxuach, said on his Tumblr that it was a Latin phrase meaning "seek higher things", which we saw in the episode is the Polaris motto, so that would make sense. However, when I used Google Translate on the phrase "seek higher things" it gave me the Latin "altiora quaerere". [EDIT: Shout out to lufluf for actually having studied a dead language and suggesting I use "quaere" in this instance instead. Thank you! EDIT EDIT: Okay, so if you're watching the show you know from episode 12 that the Latin phrase for seek higher things is indeed used to activate the Flame, but the translation used is "ascende superius". I have updated the story to use that phrase just to maintain consistency. My translation may have been wrong, but my idea was correct!] Then I saw that David Peterson, the creator of Trigedasleng, was also asked about the phrase from the episode on his Tumblr. He didn't know the answer, but asked a friend who is a Latin expert, and he said he believed the phrase was "quia nunc vale". When I put that in Google Translate it gave me "bye for now".

After this expert's translation came out I saw some criticism for Javier - people were saying the writer of the episode didn't even know what was being said. But then the thought occurred to me that there could be two Latin phrases that are used - one to activate and one to deactivate the AI. Because why would you say "bye for now" when you're turning something on? That seems a bit odd to me. So my theory is that Javier did give us a correct phrase, but it ultimately wasn't used in the episode because we never saw a scene where the AI was being activated.

The other criticism was that the actors pronounced "vale" wrong or dropped the "v". But what these critics don't know is that in Latin the "v" is pronounced more like the English "w" or a "gw" sound. It's also important to note that Google Translate pronounces "vale" incorrectly, so that could have led people astray. So, if you watch those scenes again, I'm convinced both Becca and Titus are saying "quia nunc vale" and are pronouncing it correctly so that the last word sounds like "gwa-lay". I'm betting we will hear Fleimkepa Clarke say "ascende superius" at some point this season, and I certainly hope it's when we meet Luna and she agrees to take the Flame.

Okay, Latin aside, I am incredibly excited for the rest of this story to play out! So, if you were Clarke and Lexa, when would you choose to go back? Back when the Ark was in space? Soon after the 100 landed? Before getting abducted by the Mountain Men? Would you stop Jaha from meeting ALIE? Stop the assassin from blowing up Mount Weather? Take Murphy's gun so Titus couldn't end up with it? Kill Pike before he even reached Arkadia? Who could they save from death depending on the day they return? The girls are going to have a good discussion about this in the next chapter, especially as they think about the people they cared about who were lost too soon. I already have that discussion outlined, and it was so fun to just consider all the possibilities. So, now the question is... When would you choose to go back?