Many of the Faction Paradox novels, short stories and audios can be adapted into scenarios playable with a coterie of PCs.
Several stories are about joining the Faction or include origin stories about how someone did. Usually there are test or requirements needed to be filled in order for a prospective member to be inducted. These kinds of scenarios are best suited if you have at least one recruit or little sibling
The collatoral scenario is where a war-time power (participants) wanders through a character's life and does something devestating that causes them to want to join the Faction for reasons. It's more open on how they go about doing this.