Once upon a time, my friend tenebris made a kick-ass verse called Covert, which in her words is "kinda Mission Impossible (IMF), kinda James Bond". Operatives in Covert tend to work in pairs, where the partner responsible for the offensive is called "Dagger" and the partner responsible for defensive or background work is called "Sheath". The best analogy for Sheath would be handler.
Here are some short snippets from my playtime in her world.
Ichigo goes to house sit somewhere in Yokohama, gets crashed by Renji and Rukia who are 'keeping an eye on him'. Maybe they stay, maybe they don't - they're a little like cats that way.