clever hound
This might just be me, but I think a raport system of sorts would benefit this game immensely. Considering one of the themes prominent in this game is our interactions and relationships with the characters, I think having a feature in place where certain dialogue options can make certain characters appear more or less frequently in main and side story chapters would bring things from a 9 to an 11.
While I'm all for a character getting their spotlight during their new-frame patch, the amount of genuinely interesting and good characters becoming increasingly overlooked and/or eventually "irrelevant" to the story is starting to hurt.
The main narrative of the story doesn't have to change for this to be viable, either. It can be something as simple(ish) as adding in extra dialogue and/or cutscenes based on how "close" you are to the characters via the raport system.
One of the ways this could potentially work:
When the game gives you a choice of dialogue, depending on who you're talking to or who is present at that time, your raport with them will either go up or down based on what you choose.
Once your raport with that character reaches a certain level, the more often they will appear in the story or have an optional branch of their own unlock in relevant story mode interfaces.
Now obviously, there's multiple ways to do this, but this is the way I initially thought of.
A tab in the codex can be added for tracking raport, and any extra scenes or branches can also be added to the story replay tab and unlocked based on progression as an extra.