krzykoopa
Super Freak
The origin of the blue is actually kind of funny. Bob Kane originally had the suit as black and grey but since back then the only way to show highlights was to use a different color to keep with the mostly night time theme of the book blue was used as the highlights for the suit. As Different artists went on to draw the Suit the blue spread to become the color of the suit itself instead of just highlights. So by the 1950's Batman was completely blue and grey. Then in 1964 as part of a revamp of the character the yellow oval was added to the chest symbol as part of his "new Look". Twenty years Later in both Batman: Year One and the Dark Knight Returns Frank Miller and David Mazzucchelli would take Batman back to his original roots and make the suit Black and Grey with no yellow oval, since then he's been drawn both ways, Sometimes Dark Blue and Sometimes Black depending on the artists and writers on the book.
So while Black and Grey was always there, the blue was basically taken out of context but then for years became a mainstay.
If I could I would rep you. Thank you for this post