The recovery of a loved one scenario provides a goal right from the outset, which can make it useful for plot-driven stories. You can check out the other plot scenarios here.
- A seeker attempts to find the lost one.
When thinking about roles and how your characters fill them, this breaks down pretty easily. You need the obvious two, your seeker, and the one lost. However, often the reasons why that one is lost creates the conflict. It could be that they are being held captive (tying in nicely with abduction plots), thus providing you with an antagonist. Alternately however, you may only have those two roles: the seeker and the lost one to fill as the seeker tries to understand what happened to the lost one.
Regardless of main or minor plot, a huge amount of the focus falls on what is being done in an attempt to find that lost one. This can make it massively useful for plot driven scenarios, but character motivation shouldn’t be overlooked. Think about why your seeker needs to find this lost one so much, and why this lost one might want or need to stay hidden.