There is a bar. The bar is quite pleasantly outfitted, with booths and tables and a lovely fireplace with couches in front of it. The couches must be quite comfortable, because a young woman is sleeping on one of them as though it were the grandest featherbed. Or perhaps that's just exhaustion. She—and the other woman in this currently otherwise-empty establishment—are both plenty the worse for wear. To an inexperienced eye, it might seem only as if they had been out camping for a while, from the roughness of their clothes, but if you know how to look—that's the sleep of one who's found decent sleep a precious commodity for a long time. And her sister, the one whose eyes you can see—those are the eyes of someone who's found an unanticipated path out of Hell, an unexpected part in the Red Sea.
"You don't do that without learning a thing or two about paranoia. Anyway, since you're the one who can hold the door to the universe not filled with death, it's pretty much on you to decide when to leave, although if it's all the same I think I'll let my sister sleep until it's time to go. She's had a rougher time of it the past few days than I have."
"Magnetism includes pushing off the Earth's magnetic fields to fly. Sentinels can't fly. She got us away from a couple of them, but there were others nearby. We had to keep going."
"Mm. Yeah. I think I get the idea." He gives a sympathetic glance to the sleeping girl.
"I'm really glad we found this place when we did. I'm not sure how much longer we would have lasted."
"Well, now you have your choice of... coming with me to the admiral's cabin of my flagship, or waiting and taking your chances on the next sympathetic stranger, I suppose. I can wait a little while myself but I'm irrationally reluctant to try the questionably hallucinatory coffee, so I don't want to make it more than a few hours."
"We'll come with you, I think; she can sleep later if we're really rid of those machines. We've no idea when anyone else will arrive or how interested they would be in letting us in to their universe. And, frankly, you've already made a very good impression. I can wake her now, if you'd rather leave sooner rather than later."
"Might as well let her sleep at least for the moment. I'm not in a rush on the scale of minutes, and a better prospect might come along."
"I got that impression. But...better question. What's your particular spacefuture like, compared to...well, you might not be familiar with twentieth century technology levels, but compared to there just being Earth?"
"There are... more planets? Well. I presume your world also contains multiple planets, but in mine they are inhabited and mutually accessible."
"Varied. It's hard to find a... point of entry, a place to start explaining. Um. Mars has people on it now?"
"That's cool. It's just--Earth is one of my options, sure, but...I'm not at all sure familiar is better, in this case. So I'd like to know what my other options are. Is why I'm asking."
"There are about two hundred habitable planets and stations in the galaxy. You can get from Earth to any of them in a couple of months, tops. Back on my flagship I could easily conjure you up the tourism pamphlets of the top fifty or a hundred most interesting ones, but out here I have fewer resources available."
"That's fair. Also, it's been about seven years since I had to make small talk with a stranger, and I'm not very good at it anymore I don't think."
"If there's anything else you'd like to ask me I'll answer to the best of my ability and otherwise I suspect we'll probably stand in slightly awkward silence until it's time to leave."
"Well, then, if you'd like to discuss your historical and tactical situation you can do that, and if you'd prefer the awkward silence, maybe I'll wander around and take in the sights of this bizarre location."
"I'm happy to discuss history and tactics. I can tell you quite a bit about Sentinels on my own cognizance but you're going to have to steer me a bit on the history part."
The gist of it is--they're a terror to fight. Back when there were more than just the two of them, that they knew of, a group of five or so well-trained mutants taking on a much larger group of Sentinels could almost certainly take down several of them before the Sentinels adapted to whatever their powers were--heat against cold, cold against heat, absorbing and mimicing exotic materials. The one saving grace was that Sentinels seemingly couldn't share adaptations between each other. They're built like humans. They move like humans, except when they don't. A baseline Sentinel can be damaged by so many newtons of force especially when applied to these particular areas, but one that's undergone significant adaptation is often different. They adapt to direct uses of power significantly faster than indirect ones. They can't fly, but they do have ranged attacks. They can detect mutants at an ever-increasing range, and will automatically target them over nonmutants, so if one's about to kill some genotypicals flying just into their range and playing keep-away until the original victims have gotten away is a valid, if often lethal, strategy.