Alternate Rules for Fear, Horror & Madness

[TheArcaneWeirdo]

Hello, hunters!
Welcome to the thread where I overthink about stuff trying to translate psychology into DND mechanics.
One of my favourite things about Ravenloft is that it's a setting where our characters' mental state matters just as much as their abilities, where the stress they go through has consequences even if they win.
But I also have suggestions. How to make it more playable, more realistic, more 5e-compatible...

Let's start with the latter. A simple house-rule, not a whole new mechanic.
How to do FHM saves (or will saves in general) in 5e?

I've seen arguments for both wisdom and charisma, as well as one claim that madness saves should be intelligence-based. There seems to be no concensus.
My theory is, that the reason there's no concensus is that the way we cope with fear is individualistic IRL: Some people draw courage from their force of personality (charisma), some ground themselves by paying attention to their body, emotions and envoirment (wisdom), and others intellectualize the experience to both understand it better and detach themselves from its emotional impact until after the fact (intelligence).

So my suggestion is this:
At character creation, you pick your Coping Ability, the mental ability stat that best represents your chracter's favoured coping mechanisms. When gaining a level you can change your Coping Ability, if it fits the character arc they'd gone through since choosing it.
Your Coping Ability is not necessarily your highest mental ability stat or the one you use as spellcasting ability. It's the one your character emotionally relies on when all else fails. Try to think about it from personality view rather than midmaxing view.
I like this rule because it gets you thinking about what's going on in your character's head when you roll a FHM save, which allows you to roleplay better both their fear and their attempt to overcome it.