An AU where Keith was born blind and Shiro is his childhood friend who dedicated his career to help Keith finally see.
This idea started while I was watching this video in youtube where little kids would explain and describe what a color looks like to a person who was born blind.
I imagine Shiro describing colors to Keith since they were little. At first, Keith wouldn’t be able to understand Shiro (”red is liiiike, what an apple looks like!” “…I don’t know what an apple looks like.”) but gradually, Shiro got better in describing. He chose feelings (sometimes even taste) as examples and Keith grew to love how Shiro describes colors, he often asks Shiro to do it.