I placed the last signature on the file and closed it, then watched as Booth watched me scrabble his chopsticks around in the bottom of the box of Mee Krob, waiting for me to call him a pig or try to fight him for the food that was left. It was as normal as it ever was-- except more, now, though I'd never have guessed it before.

We talked a lot more and argued a lot less about things that didn't really matter. We still argued about motive, and how fast I was working, and whether I should have a gun or not-- but personally? It was just less ... precarious even as much as I'd needed him before all this happened. I learned to ask him more questions that had nothing to do with religion or sex, and everything to do with whatever he might want to tell me. And he actually told me things-- I think I learned more personal things about him, none of which changed my initial impression of his inestimable character, in these past four months, than I'd known in the past four years. And each time I told him it was okay, he seemed to believe me a bit more.

And... he'd been there for me. When my Dad had his heart attack, Booth was the first person I called, the first one to arrive at the hospital while we waited to hear. He was still my best friend in so many ways. He took turns with me when my Dad came back to stay with me at my place, running home at lunchtime to make sure my Dad was okay and to bring him lunch, since he practically blew up my microwave that first day we left him alone, and took turns running my Dad to appointments when the incision from the bypass in his leg still left him too sore to drive.

Booth hadn't been dating. Angela either. It was all strange, and yet not. Angela and I were actually closer than we'd been in a long time, even before she and Jack got together, though it had been hard for her and me when she finally broke up with Roxie and tearfully admitted that she thought she still might love Jack just a month ago. But ... we'd gotten through it, and I hoped I gave her some good advice-- I wondered what the future would bring, now that Jack and I were over.

After we'd agreed that we'd found what we needed from each other, and that what we wanted exceeded what the other could give, Jack had joked about that Crosby, Stills, Nash & Young song, "Love the One You're With," claiming that had been what had kept us together even as I agreed with him we should end it.

I'd shaken my head. "No. I love you unqualifiedly, Jack, you know it's not a question of settling. It's … the time paradox we discussed. We're in a different now than we were four months ago, and … it's a good thing. But … divergent paths, right?"

He'd nodded solemnly. "Yeah. Different stories. Different kind of love, too."

At which point he'd started singing a completely ridiculous Cher song called "Different Kind of Love Song" that even I knew, and I made fun of him again for trying to impose a time paradox upon our lives with all his "what if I'd kissed you when I came out of that hole" or "what if Booth kissed you when you came out of that hole." I didn't repeat our discussion earlier that night about all the 'what if's' we both still had about Zach.

When he'd stopped singing, I told him "I wouldn't change any of it. It's been a pleasure, Dr. Hodgins." Which of course made him cry, the way I echoed his words when we both thought we were going to die, and that made me cry-- but it was a happy cry, though it wouldn't make sense to think crying could be happy. But we'd made love one last time, and fell asleep holding hands, as I said to him, "Just think, Jack. New day, no more old cars tomorrow, and lots of new dynamic systems to affect."

He'd smiled and kissed me. "No stasis, new day, new cars. That's right."

When I came out of my reverie, Booth was looking at me. "I was wondering if I was going to need to wave a spring roll under your nose there, Bones," he said with a grin.

"Sorry," I said, returning the charm smile, and enjoying the fact that his became even wider. That had been happening more, lately. He'd been letting me just be a friend, rather than someone he always had to take care of. I looked at him one more long moment, then decided to tell him. It was what friends did—shared information-- no matter what else they were or might be.

"Jack and I broke up."

His chopsticks in the Mee Krob stilled as he looked at me. "I'm sorry, Bones, when?"

"A few days ago."

He looked at me, assessing the work we'd all just put in on the case, all the long hours the whole team put in at the lab, even Booth, who'd in the past few months taken to using my laptop to run more database searches and perform other FBI work on the overnights—or sleep on my couch, waiting-- while the rest of the team worked on the scientific data. He'd been at the lab or with me practically the whole time. If I'd been upset, he'd have seen it.

"You guys ended on good terms, then."

I nodded. "Still friends—better than when we started for sure, and that's more than worth it all. It's always good to have friends."

His serious expression was just concerned, not … acquisitive, not that he ever had been. "You're okay, though?"

"Yes, really. I mean, there's always a period where you wonder, but … we hashed it out pretty thoroughly. We just … we were travelling parallel paths for a while, and it made sense to take turns carrying each other, but… well, roads diverge." I shrugged. There was more to it, of course, but I didn't need to bomb him with details.

He'd asked me over late night post case Thai and paperwork, two months into things with Jack, if I was happy. He'd asked it very seriously—so I gave him a serious answer.

"I think so. I've finally realized it's impossible to fully plan for the future. Right now? I'm content."

"Very Zen, Bones," he'd said with a smile.

"And you?" I'd asked.

"I think so. You're right about the planning thing… I'm just trying to concentrate on enjoying what's happening now."

That conversation was echoing in my head as I watched Booth try to decide if he was going to ask me anything more.

"So … what do you guys do next?" he asked.

I snorted. "First, I've got to get him to stop calling me 'babe.' It was one thing when it was baby just like everyone else, but 'babe' is just different."

He laughed as I made a face, then said, "Sorry, Bones, I'm with Jack on this one. You don't like a nickname, you've got to karate chop someone right out of the gate. It's too late now."

"Shut up and hand me a spring roll," I said, sticking out my tongue. "And go get me a beer."

He handed me the spring roll, but made to stay put until I went to karate chop him, at which point he brought us both new beers, laughing. We finished the food and were halfway through the last of the beer when he looked at me solemnly and said "Can I ask why?"

"Sure," I replied. "But it's a squinty answer, so you're going to have to bear with me, because it's the answer both Jack and I agreed was why … our paths diverged."

He wrinkled his nose but said "Fine. Just dumb it down for me where appropriate."

I took a long swallow of beer, composing my thoughts before I began. "In maths, physics, and philosophy, there's a concept—a theory that hasn't yet been disproven-- called the time paradox. What it posits is that logically, time travel is impossible, because if it were, going back to the past would inevitably change the future, and could well make both the time travel and the time traveler impossible—the question of if you killed you grandfather, you never would have existed to time travel in the first place. And philosophically, there's an additional aspect-- it's that 'what if we went back and killed Hitler' thing. Even if you did, it would change the future so drastically that there would be no way to know whether the future you'd get in the outcome would even be worth it."

He nodded, following. "Yeah—I've heard that Hitler analogy before."

"Well, there are all sorts of attempts to subvert the theory—ideas like superstrings and multiple universes and other things—but suffice it to say there's no practical facts to disprove the theory. It's just … it's impossible to change the past, and as a matter of theory, doing so is destructive. Trying to change your then present by going back and re-writing things in the past has potentially disastrous, and at least completely unknown and uncontrollable consequences for the future."

He nodded. "You'd basically be killing yourself, or changing completely from who you were."

I sighed as I realized he was getting it. "Yes. Exactly. Now… this is a different theory, but it's related. The butterfly effect refers to the relationship between things happening in the present that may go into the future. It's part of something called chaos theory, and most of it's not important except… the butterfly effect posits that there are factors which are sensitive and dependent on each other at only one given time. If one of them changes, then everything else in the system is also affected. Basically, things are always changing, but at any one point in time, there's always the opportunity to make a difference by acting one way instead of another. And that decision can produce large variations in the long term behavior of the system."

He nodded. "It's the 'what if' thing, except at a point where you still could do something about it."

I wanted to lean over and kiss him—for so many reasons, but for getting where I was going, primarily.

"Exactly!" I said, excited to finish explaining the rest. "Well… people are conscious actors unlike physical particles or other non-sentient phenomena, so there's an opportunity to … take advantage of some aspects of the time paradox. You can't change the past, but you can try to learn why you ended up where you did so it makes you better able to make a decision that positively affects the outcome of the interdependent system for the future."

He was listening, seriously, and I wanted to get to the next part before my courage gave out.

"You never know how your reaction's going to tilt the system—there's a lot of other things going on that you just can't control, but … you might as well try to tilt it the way you want from your current vantage point, rather than worry too much about all the other butterflies affecting the chaos. You can't control, or predict, but you can at least try, based on what you've learned from the time paradox."

Still solemn, he spoke into the pause. "Okay. I get it. So what does that have to do with you and Jack breaking up?"

I swallowed. "The time paradox is basically a bunch of 'what ifs'—they don't change the present, though they can inform it, working backwards. You know the present—the result. You can work your way back to find what all the different factors were from that one point you just wish you could go back and change. And … going forward? Those are 'what nows,' the butterflies. If you know where you are, you can at least put yourself out there in the direction you want to go a little bit more.

So… Jack and I both had a lot of the same 'what ifs' all coming from the same point in time—the Gravedigger—and the 'what now' point all coalesced when we were keeping company that night at the lab. I can't really explain all of the things Jack was wondering about—those are private to him, but we both had a lot of questions that came down to the same general questions, all of them arising out of our interactions with people after we came out of the ground. What if I'd spoken when I stayed silent? What if I stayed silent rather than saying something hurtful? What if I thought harder before I said anything at all? What if I'd paid more attention to Zach and less to myself? What if I'd paid more attention to the other person in the ground with me, been more of a friend, if if if…"

I looked at him and willed him to understand, while weighing my words so I didn't say anything that would hurt him.

"I was tired of asking what if. And Jack was too. We were both tired of waiting and wondering, we wanted to just … do for once, just try with the information we had, not constantly rethink things or wait to see how other people might act if we just assessed things long enough. So we … tried. Together. And it was lovely. He's a good friend, a fun person to be with, attentive and kind, all of those things, and we have a lot of things in common. But experiences can be the same and yet have different effects on you. The same experiences and fears we both had, our 'what ifs?' -- not wanting to be alone, being afraid of the dark, wondering whether we were too damaged to make someone else happy, much less be happy ourselves? We resolved all of those. And when we did, we found out that as much as we'd enjoyed each other's company, and couldn't have made it that far on our own, when we stopped to see where we were, he wanted to go down one road, and I wanted to go down another.

We each know how we want to deal with the 'what nows,'—at least I think I've maybe learned a bit tracing my way back along all the 'what ifs' I had, but … we … wanted to affect the other dynamic actors in the system in different ways. So, Jack brought it up, and I agreed, and now he's going off on his path and I'm going on mine. Because … here's the thing we both agreed we were guilty of, beforehand. The butterfly effect posits a dynamic actor to effect a change in the system. Without trying to affect things, you've got no control over how it comes out. We both agreed that at various points, he and I were static rather than dynamic. But… now we don't need to be, quite so much. I know it's awfully technical, and it's ridiculous that I needed to figure my heart out through theories of physics, but … it is what it is. At least I figured it out."

He'd been listening intently as I answered-- when I finished, he made a small face, half silly, half solemn.

"That was squinty. But I know what you mean. And … I get what you mean about all the 'what ifs,' but… I'm still sorry that there were points when I should have done something, Bones. I know that it doesn't change anything now, but nothing says you can't learn and regret at the same time."

"That's what I told Jack… except in a more squinty manner, of course."

"Of course," he said lightly.

I leaned over and clinked the butt of my beer against his, sitting on the table before him. "Regret's something different, though… feeling badly, feeling pained that you hurt someone along the way, or that you lost the chance to do something that might have made you happy doesn't necessarily mean that you shouldn't be where you are, or that the things that didn't happen before might not happen again. You just have to … know where you are."

He leaned in from where I'd rested my elbow on the table, his eyes dark and curious. "And you know where you are?"

I shook my head. "Absolutely."

It was true—though it was painful at the time, there were a number of initiating dynamic steps in a new systemic reaction, all those months ago-- admitting I loved him, and that he loved me, but choosing Jack for the moment-- when Booth let go of me out in the gardens, he seemed to let go of a lot of things. And in letting him walk away—it felt easier, now, to go after him, because in letting him walk away, and in walking for a while with Jack, well, I knew where I was now, and I at least had a clear view of how I wanted things to work out. There were lots of things I couldn't control, but at least I could try.

He smiled as I answered him-- a genuine smile that warmed me all the way through. "Good. I'd hate to shoot Hodgins, otherwise."

I couldn't resist the urge to respond. "Booth-- I'm a dynamic actor, I'd have shot him myself."

His roaring laugh as I waggled my eyebrows at him was the first step in a new direction—one I hoped we'd both walk along together, this time. And be more, this time.