Inspiration, at its most fundamental level, is just the latest iteration of "action points" (except extremely simplified). When a character has Inspiration, they may expend it while making an attack roll, saving throw, or ability check. By doing so, they receive advantage on that particular roll. A character gains Inspiration by playing out their personality traits, ideals, bonds, and flaws. A character cannot have multiple "Inspirations". They either have it, or they don't.
While I like the mechanic, I feel like it could be taken a step further. Although there are a few different paths one could take Inspiration down, I just want to entertain one specific idea for the moment. When designing new house rules, I sometimes like to take influence from other games. While reading Inspiration and thinking about different ways to handle it, my mind constantly drifted back to FATE and how it handles aspects.
For those of you who are unfamiliar with FATE, aspects are simple words or phrases that represent a key feature of your character, something that can either help or hinder you depending on the situation. During the game, you can spend fate points to "invoke" an aspect, gaining a benefit in a situation tied to it. Alternatively, the Game Master may "compel" an aspect, rewarding you a fate point if you take a penalty in a situation tied to it.
Hopefully, you can see where I'm going with this.
What if someone decided to adapt FATE's method of handling aspects to 5e, incorporating Inspiration into the mix? During play, characters can invoke Inspiration to receive advantage in a situation where on of their personality traits, ideals, or bonds would be helpful. However, the Game Master may reward Inspiration to compel a character's personality traits, ideals, bonds, or flaws during situations where they'd be a hindrance, giving the character disadvantage. Furthermore, characters can now have up to three Inspiration points at one time. When being compelled, they can choose to spend an Inspiration to deny it.
While this change does add a little more complexity and I admit it's not for everyone, I feel like it makes Inspiration a much more interesting rule and gives personality traits, ideals, bonds, & flaws more mechanical weight. I thought about adding alignment into the mix as well, but I'm not sure I want to travel down that rabbit hole (at least, not yet).