Hacking in strings

So, I'm running a solo game, and since hx isn't really worth much without other PCs we've thought about hacking in Strings from Monsterhearts. Here's my first draft. We're gonna run with it for the moment, but thoughts are appreciated.

When you go aggro, on a 7-9 they also give you a string; manipulate/seduce on a 7-9 give them a string, on a 10+ take a string on them.

Otherwise, when you bear your heart to others, truly, give them one string, when someone puts themselves in a position below you, take one string on them.

At the end of the session, choose one person who you've learned something about, take a string on them. If you think they've learned something about you, give them a string.

Sounds great Aaron!
But rather than the mechanical bonus (or perhaps instead of) the string implies, how about a narrative effect? Perhaps like the alternate Hx move? Like when you gain a string on someone they have to choose:
* Tell you who they fear
* Offer up their hiding place
* Reveal a secret
* Expose a weakness
 
That sort of thing? Of course this applies for the Player if they give a string to an NPC (MC) too...

I'd definitely incorporate the alternate Hx for NPCs to, and the associate "when you retroactively set something up" moves.