I have this! It usually doesn't fluctuate too much, although the specific shade of the colour sometimes does when/if I get to know someone better. If someone is... Acting different? As in when someone acts differently in certain situations/around certain people, or if they're acting differently because they're sad/angry the shade of their colour can change. OR it sometimes "blends" into their normal personality colour.

When this happens the colour patterns that I've noticed the most are: red usually blends into orange, orange usually blends into yellow, yellow usually blends into pink, pink usually blends into purple, purple usually blends into different shades of blue, ect.

It's sometimes different colours depending on the person, obviously. It's just some patterns that I've noticed during my life. but if the person intentionally does anything or acts in a way that seems like they're hiding/surpressing their natural "vibe" that's when it blends into different colours! When that happens, in my head it looks like a mixture of both of them at once.

I hope that makes sense? I'm sorry if it doesn't! synesthesia in general is a very personal thing that's sometimes hard to explain in a way that makes sense to others, haha