I’m watching a show on a condition named synesthesia, and it’s fascinating. Here’s a description I found online:
Synesthesia is an involuntary joining in which the real information of one sense is accompanied by a perception in another sense. In addition to being involuntary, this additional perception is regarded by the synesthete as real, often outside the body, instead of imagined in the mind’s eye.

One woman on the show sees all letters in certain colors, and each letter has the same color every time; they don’t just change. On top of that, when she hears words being spoken, she sees them being spelled out (in her colors) out in front of her face, which is consistent with the definition above that says these sensations are often outside the body, not just in someone’s mind. She also has family members who have the same condition, and they have their own color assignments. One man on the show tastes certain foods with certain words. Brian said he would figure out what word brought on a chocolate taste and then just say that word all the time. The man does have a chocolate word, but some words aren’t so becoming. One word makes him taste a combination of celery and toffee, so not everything is that great. Anyway, I guess if you’re going to have some type of medical/neurological condition, this one would be an interesting one.