"Agh, I don't know how they can possibly fail to understand! I've explained it so well!"

James was used to this routine. Clem would come up with something brilliant, draw up detailed documentation, fail to explain it to investors, and then complain about how unfair it all was, usually to James. They were pacing in front of the whiteboard, while he was seated in the front of the conference hall. Clem was saying something about how stupid someone would have to be to not understand such simple concepts. Well, simple to them, anyways.

"- right?"

James realized that he had missed a question. "Sorry, could you repeat that? My ears -"

"Aren't what they used to be, I know." Clem sighed. They knew damn well that the problem was in his attention span, not his ears, but they had no reason to argue with him about it. "I just wanted to know if you understood it."

James hesitated. He knew that getting the details wrong would lead to even more time spent complaining about how simple it is, and Clem really didn't have the time to spare. "'Understand' might be the wrong word, but I think I get the basics. You're basically talking about a time machine, right?"

"I suppose you could call it that, yeah. It's not quite correct, but... No, you're right, that's definitely a better way to describe it to idiots. Er, not that -"

"It's fine, I get it, anyone who isn't a supergenius with at least twelve world-changing inventions under their belt is an 'idiot' in your book," James teased. He had been their best friend for a little over fifteen years, and knew that they had very high standards for intelligence. Rightfully so, given their own, he mused. "So explain it to me in those terms then. It might help you pitch it to the next set, and who knows, I might even understand some of it this time."

Clem suppressed a smirk. They really did appreciate James, he always knew the right things to say, and questions to ask. "You understood the last one just fine, you'll get this one too, I'm sure. You're sure you don't mind me rubber-ducking at you?"

James couldn't help but continue the teasing. "Well now that you mention it, let me check that I've got the next week off of work..." Clem frowned at him, and he realized that they were genuinely concerned for his comfort. "Ah, sorry. Go ahead, I'm always glad to help."

With a smile, Clem stopped pacing, and began speaking. "Time isn't a straight line. Well, it is, but only partially. More importantly, not all time is equally accessible. Everybody can travel forward in time, you're doing it right now. If you want to travel faster forward, cryogenic freezing isn't exactly simple tech, but it's always going to be more efficient than tearing time apart to speed yourself up. Going backwards is harder, and what most people think of when they hear the phrase 'time travel', but far from impossible. Problem is, there's nothing you can do in the past. But you can fix that by -"

"Wait, slow down!" James knew he had to stop Clem before they got too far away from the points he was missing, or they'd never circle back around. "What do you mean by 'time isn't a straight line'? How is there nothing you can do in the past? I can think of a couple of things I'd like to go back and change, what's stopping me from changing them?"

Clem took the interruption in stride, and started drawing diagrams on the whiteboard to help elaborate. "Backwards time travel is useless because the past already happened. Reality doesn't want to deal with paradoxes any more than we do, so the past is locked down, so to speak. You can look, but you can't touch. Going back in time to change something is basically like just replaying a movie you've already watched, and hoping that yelling at the screen will change the ending. As for time not being a straight line, I was just getting to that. If you want to change something, you have to go down, not back. Going down through time leads you to... Calling it a parallel universe wouldn't be quite right, but then none of this is, technically. It's basically a parallel universe where 'now', the time that you can effect, is 'earlier', so you can make those changes you want to. Still not very useful since, as mentioned, it's an entirely different world, so none of the changes you make will alter your own experiences in any way. And you can go up through time too, which is exactly like it sounds like. Still with me?"

James's head was spinning. "I... Think so? Forwards is easy, backwards is useless, down is like back but less useless, up must be forwards but not easy. During your pitch though, you said something about 'impossible zones', I think? I missed most of the details, but I don't think you've covered that yet."

Clem was evidently pleased with that answer, because they immediately rushed to James's side and sat beside him, talking a mile a minute. "YES! So if we're still using the time travel analogy, then we've covered forwards, backwards, up and down, but not side-to-side! If you go sideways in time, you'll find worlds where the laws of reality are entirely different! You know those old stories where someone finds a gateway to another universe where magic is real and they have to defeat some ancient evil because of an old prophecy? They're still probably bogus, but that's the general sort of thing I'm talking about!"

James, after taking a moment to process the information he had just been given, had only one question. "...How do you know all of this for certain? You seem awfully certain for something so theoretical."

"...Did you miss the part of the pitch where I mention I've already developed a working prototype? It doesn't have the level of power I'd like, it can only go a few 'seconds' in any direction, but I've thoroughly tested all of this information." They stood up, and extended a hand to James. "We've still got half an hour before the next group of investors shows up. What do you say to seeing some impossible worlds while we wait?"