I have made a visual novel and I included a couple of typefaces players can choose from for legibility (I include some Dyslexic-friendly ones).
It would be kind of interesting to create a set of fonts from the same legible typeface that denotes some kind of emotion? This for me was the biggest challenge as a VN writer, because we're trying to squeeze as much life from words as we can. So for example, I'd add screenshake when a character was shouting, or add a sound effect when a character was sighing.
It would be cool to have the letters themselves add more character to the text, though. Like if an NPC is sad, the characters sag a little bit, or if a they're angry, the font's serifs all get pointy and jagged. It was something I thought about while making the game, but ultimately didn't have the resources to execute. I hope that's a helpful pitch!