The short version of the perennial ally question, whether you’re obsessed with that whole sole power thing or not, is that having allies is useful. They’re good for covering your fronts, particularly if you share a border, or for making your enemy worry about his, if you’re on different borders. They might know something you don’t, or be able to handle something you can’t, and they’ll be oh so grateful if you return the favor. And, of course, more allies means more soldiers in the mix means a greater general quantity of cannon fodder.

Now, about choosing them.

On the one hand, you’re going to want to choose your allies for a number of factors. Strength, of course, is one of them: an ally that can’t mostly keep up with you in a fight isn’t going to be much use defending you, now, is it? They’ll need to actually be willing to come in on your side should push come to shove, preferably without you having to make examples of their leaders (a generally counterproductive measure when you’re already fighting someone else; see below). It helps if they’re either aware and accepting of your narrative status or completely oblivious to what you really are with no chance whatsoever of finding out otherwise (this includes you and yours being on your best behavior, mind you!); in-between courts the chance of them turning on you.

But on the other hand, there is something to be said for making allies of parties who are neutral because nobody’s bothered to come a-courting them. Even better if nobody thinks they’re worth anything despite their being in a very useful strategic location. Yes, they don’t appear to be a significant threat; that’s why nobody’s tried to enter into an alliance with them yet, after all. But a country like that has two major advantages: one, there’s something flattering about being approached as equals by a more major power, and two, it’s quite possible that they themselves have something to prove. If you can help them prove it and they know it, all the better, but you’re probably fine if they just think you can and will.

Note that allies are not necessarily friends. That doesn’t mean don’t let them think they’re friends; it just means that you don’t need to make the extra effort for them unless you know it’s in your best interests. Try to stay in what appears to be good faith until the end, though—and do consider postponing your inevitable betrayal, if you’re the type to go that route, until after the most obvious moment. Sure, the obvious moment is when they’re the most vulnerable, but someone’s bound to expect it. On the other hand, waiting makes it even clearer that you don’t plan to make a move, and they might let their guard down a bit.

Plan for your allies, but never let your plans depend on them. You can let them think your plans depend on them, though. It’ll motivate the ones that actually like you, and you’ve got a decent chance of figuring out who doesn’t like you from who misses the “planned-for” engagement without a really good reason.

Alliance. Complicated, but workable.