One of the fun things that marks FATE different from a lot of other RPGs is what set of rules the mechanics are designed to replicate. Simply put, where most RPG mechanics are designed to replicate the physical reality of the world - in some fashion or another - the rules of FATE are designed to replicate the rules of story.
In FATE it doesn't matter how slippery the ground is or what the actual top velocity of a vehicle is, what matters is that the "Ground is Treacherous" and that both people are in "Really Fast Cars." Beyond that the story cares not.
Because of this shift, which is shown strongly in characters that have aspects of who the character is rather than a stat line, I've developed a theory of sorts. The theory is that you can tell how well you understand a character, and how narratively strong that character is, by making a Fate sheet for them.
To this end I've been mentally converting the PCs in my Friday L5R game. High Concept is easy, that is their role/clan/school (i.e. Mirumoto trained Hitomi of the Dragon Clan, or Storm Legion Court Trained Yoritomo Bushi.) Simple stuff really, but it works.
Where things get fun is the Trouble Aspects. Why? Because this is one of the places where Fate characters and other RPG characters often deviate in design intention. Fate design wants you to get in trouble, it is the path to power in the system. Other games reward minimizing these things. And yet, looking at most of my PCs in my game a bunch popped to head immediately. For some it linked back to the high concept, such as the Matsu's trouble aspect being "A Matsu's Pride", for another it ended up being "The Weight of Family" to represent all the troubles the character has stemming from their parents and how they were raised. In one case the aspect represents the character's personal quest ("A Sword Named Kiri.")
The experiment has worked out wonderfully well so far, and it has also given me ideas on how to approach the characters in game for more fun and obstacles. Perhaps it will do the same for you.