"Thankfully we don't actually have Sentinels, those being the killer robots, back home."

"I don't think we have any kind of military robots back home. I could be wrong. I'll have to check."

"Is 'inventing things' usually a viable power option? Because it isn't in my world," Helen says.

"It is for my kind of cape. One day I got a taste of my worst nightmare, the next day I started building little doodads to fix my clumsiness and designing my own computer from scratch."

"Oh, you had that too? Mine went away when we turned sixteen and our basics came in; gemini are peak-human physical condition and coordination from that age on. But we don't have tinkers."

"Our world has the occasional engineering genius, and sometimes there's strong evidence that the genius is a power, but the stuff they make still works like normal stuff, you can teach people to fix it and make it and stuff."

"Yeah, we have nothing like that."

"Not even, like, Edison and Tesla, or nobody who you think it might be a power?"

Snort. "Nobody who we think it might be a power. We had Edison and Tesla."

"If I think about it too much tinkering is actually very bizarre. It's sort of like a really, really supercharged version of... noticing how much linguistic information you know just by being a native speaker, or being able to sing a song in a different key even if you couldn't figure out the transposition on an instrument. But that's too - passive, in addition to being too trivial. That's something that happens without you noticing. I definitely notice when I'm tinkering and I'm actively directing myself, but simultaneously it's sort of like a trance state, people call it 'tinker fugue'..."

"That sounds very strange."

"It's so weird. But it's amazing for getting a lot done in a short time. When I let a fugue get going I don't have the slightest impulse to slow down until I'm done. My software bot reminds me to eat and sleep, but I don't waste time playing video games or anything."

"Sounds like really good flow state. On meth."

"Yeah, that's a good way to put it. You can watch me do it if you want to fund Flicker's little ash robot. I think I can keep the whole thing under two thou if I can borrow tools without buying them, even less if Bar has good alternative materials suggestions."

"Sounds enlightening. Sure. Bar, whatever she needs to build the ash robot is on me."

"I suspect it's remarkably lucky that while Bar doesn't allow arbitrage there's no such restriction on various worlds one can visit through her."

"What do you mean?"

"Bar offers 'reasonable currency-dependent prices' for things. For example, you can buy an apple from her from about what you could get it for at a local supermarket. You can not, however, sell it back to her at the price you could get for it three counties over where their apple blossoms got killed by late frost this past spring."

"No, I know what arbitrage is, I mean, is there not a restriction on where you can go through here? It seems like it's limited to worlds belonging to people who show up at the same time. If Lorica waits here for a month and nobody who can kill Endbringers or has a world with people who can shows up she's out of luck."

"Oh, no, there is, but Emily actually has a device that somehow gives her the attribute of counting as a native of the universe we're staying in as well as our actual homeworld, so we can get doors to either, and there's a non-negligible opportunity for arbitrage between the two."

"Oh, neat. Is that how you're funding my expensive ash Roomba?"

"Among a few other things, such as the fact that my family had money to begin with, yes."

"That's handy. In our world it's sufficiently potentially dangerous to raise twins in iffy circumstances that if you try to do it while poor the government will either outright pay you child support or take your kids. We're not that far down the socioeconomic ladder but it was occasionally tight. I'm very marketable, though, global teleportation isn't common enough to drive down the price, so I expect to be rich after I've had a while doing that."