What can be done with Hx for NPCs?

So, there's the custom move on p. 277 that goes, "When you Read a Person in a charged situation...if you're reading an NPC, on a 10+, in addition to your hold, you can: -give yourself Hx=0 with them, if you have no Hx with them, -add +1 to your Hx with them, if you do have one (max Hx+3).

Since Hx is generally most helpful when aiding or interfering with someone's roll (which NPCs don't do), or gaining XP when it rolls over at +4 (which the above move doesn't seem to indicate), what good would it do to have Hx with NPCs?  What can be done with that?

There's a move right next to it that says something about when you try to get the drop on someone in some retroactive way, roll+Hx with them.

The driver and maybe the battlebabe and I forget who else already have moves that let them roll+Hx to go aggro on or seduce or manipulate a PC, so it'd open those kinds of moves up to NPCs.

Thanks Vincent!

That's true, there is the move just above about "when you declare retroactively...". After I posted I went through the playbooks and found the other "roll+Hx" moves, too:

-In the optional Extended Combat moves, you roll+Hx when following up on someone else's move.
-The Battlebabe's "Ice Cold" move allows rolling+Hx instead of +Hard when going aggro.
-The Operator's "Easy to Trust" move allows rolling+Hx instead of +Hot for seducing and manipulating.

And the LE playbooks give us one more:

-The Maestro'D rolls Hx for "Just Give Me A Motive", allowing them to poison someone's food or drink.

I expect an AW game with Hx for NPCs would probably need a couple more custom moves; possibly one that allows for Interfering/Aiding NPCS somehow?  (Although that gets muddy; the PC version is nice and clear that the only time you're interfering is if someone is rolling dice.  An NPC version would need to be careful not to overshadow the other basic moves.)

Of course, the book does say just after that adding NPC History is moving toward something that isn't fully Apocalypse World any more, so maybe that implies a bevy of other Hx based moves that aren't present given AW's structure and scope.   

I bring this up because in the game that I'm playing there are only 2 PCs, and they both kind of do their own thing and we have some sessions where they're in two different places and don't really interact directly much, and come end of session we don't really feel they've gained any insight into each other.  Plus, giving out a token +1Hx to each other every time gets old.  So, I was looking at giving NPCs Hx as a way to keep the stat relevant in our game.

Does anyone know of attempts to integrate this?  Any tips?

As far as I know, you're breaking new ground. Try stuff, and tell us how it goes!

We've always used Hx with NPCs.

For us, it's the same as with a PC, except it's mutual (you record the Hx you have with the NPC, and that describes the reciprocal relationship, too). When you want an NPC to aid you, and they're willing, you roll+Hx with them. Results as normal, with them getting exposed to danger or whatever, depending.

Several NPCs have died this way. ;)