Jon Snow
Sure, I could use a Hostage Rescued but does this work:

Fleeting Restoration - returns a unique stark card, then kill it at end of the phase

They Live - Unique Stark cards cannot be killed

So, when I return a char using Fleeting Restoration it has this lasting effect of having to kill it, however, if it cant' be killed then i think it should stay in play. Pretty sure this is right, but thought I would check

ktom
The combo of "They Live" and "Fleeting Restoration" does not work. The FAQ has an entry that specifically says that "until the end of the phase" lasting effects become inactive BEFORE "at the end of the phase" passives trigger. So when the "at the end of the phase" kill from Fleeting happens, the CBK from "They Live" is gone.

The trick DOES work with unique Stark nobles, Power of Blood as a plot and Fleeting Restoration (because the CBK from the plot does not go away before the event's passive kill). HOWEVER, please note that if you're going to do that, the "that character cannot be declared as an attacker" condition from the event does not have a duration. If you use the plot to make "Fleeting" more permanent, the character will STILL not be able to attack.