I have a potential mechanic for the game to try incorporating, if you don't mind hearing it out.
Regardless of whether or not the PCs are all Persona Users, PCs begin play aligned w/ an Arcana, one they either choose or the GM rolls for them. This starting Arcana serves as it does in the Persona games, as a general skillset and attributes list, but more importantly, it remains a fixture for the character throughout the campaign.
In systems like Shadowrun, a GM would pass out Karma exp at the end of sessions where players were judged to have done a good job and achieved something. Obviously we can't quite handle things the same way here, but my suggestion is to organize the RP in an episodic format, and at the end of each episode, the GM has PCs roll for their fortune that will continue into the following arc. This post-episode fortune is meant to have a new tarot Arcana be drawn, but its significance represents a sort of clue to future events for that individual character.
The idea is that if PCs are designed to exist as part of a larger universe, and not solely for the explicit in-universe events the campaign goes through, then that should mean each one has their own type of sub-plot. Most such things don't really tend to be developed in some RPs I've seen, though, so the episodic Tarots are meant to provide a "preview" of each individual PC's circumstances, rather than have them all be treated by the system as parts of only one entity (ie making them go through every little development together).
Thoughts?