So I'm thinking about a TSoY game in which some of the players are bound to other players - something like the relationship between Warders and Aes Sedai in Wheel of Time.  I immediately grokked to giving Key of the Guardian in a situation like this.

So here's my question, as it relates to Keys that have another play as the primary focus:  This is a good thing, right?

I recall reading somewhere on here that folks highly recommended taking keys that hit like this, and that it'll create fun and dramatic interactions, and that clever players will rake in the XP.

Samwise the PC takes Key of Unrequited Love for Frodo the PC.
Min the PC takes Key of the Guardian for Rand the PC.
etc.

My only hesitation is that some of these keys hinge on something to the effect of "making decisions based on that person".  Do I need to lay out social contract/expectation for how many times I think its appropriate for someone, during the course of a session, to take the 2/3 xp hit for having had their decision influenced by their charge/love?

To answer the question, I've never had any trouble with players hitting Keys too often. There are plenty of ways to remedy it if it's happening, with the main one being for the whole group to realize that the xp system is totally malleable to group expectations - the players should find a pace of xp gathering that feels natural to them and let the system adapt to that, not the other way around.

In practice I'd say that you just need to play a session or two and if it seems that everybody is getting too much xp, adjust the xp cost of an Advance upwards. That is really pretty much everything you need, assuming that players are genuinely playing the game instead of practicing some kind of xp gathering rules lawyering. As I've yet to see the latter in a real game, I'm not overly worried.

As a fellow player, you have influence in where the other players gather their xp. If you're not rocking on their choices, feel free to ask them to elucidate a bit on why they're getting xp for something, and whether they really feel that this was an important turn of events in the game. Courteous players will either share their excitement with you or stop taking xp without good reason.

Thanks, Eero.