There is a trend in solo play to move towards simple RPG, things like Tiny D6, Adenturers!, and Hero Kids (don’t be put off by the Kids bit in the name, it is a very competent little RPG).
As game systems get simpler, they by necessity have less rules, and some of those rules can be a soloist’s friend. One of them, Character Weaknesses or Flaws, I find really useful.
D&D 5e has flaws, they are rather bland, but they do exist. My Cleric is rather obsessive.
Flaws in other systems can be much more flavor-rich and even have mechanical impacts on gameplay. In Hero System/Champions many disadvantages had activation rolls that you would test to see if that disadvantage came into play during the adventure. Rolemaster’s talents and flaws modified rules or added penalties to actions. Year Zero Engine games have varieties on dark secrets in your character’s past to rivalries between party members.
Some of these are easily layered on top of a simple RPG system, especially character relationships that have no mechanical impact but add a layer to the social dynamics in a group of characters.
If you are using Mythic GME or something that uses the same kind of oracle hooks into the story arcs, these flaws and and disadvantages give the oracle something to work with or act upon. That is a mechanical reminder to you to involve those flaws in your gaming.