This isn't really an AU or really even too much of a Klance thing, but...

I really want to write some sort of short story/one shot where Keith's natural hair color is white. That when he joined the garrison, he didn't want to be ridiculed for the strange hair color, so he dyed it black (eyebrows too). He ends up liking the look much more, and decides to stick with it.

However, due to the nature of their departure from Earth, he didn't really have time to necessarily stock up on hair dye. Eventually, Keith's hair starts to fade back to its normal color, and the team (except Shiro, who already knew about the hair dye) starts to freak out.

As it fades more and more, Keith expects a whole new wave of teasing and insults from Lance, but the reality is something rather different...

"I... I actually kinda like it. It's cute on you..."

Inspiration:

Also, inspired by a conversation with small_fox_shark :3