Brat Style came from the Brat Style shop in Japan.
Brat styles usually have only minor frame modifications. (shorten) a thinner flatter seat installed, most have adopted the black rims, and I have seen all kinds of crazy handle bar options. (just whatever suits the owner comfort and riding style)
I am sure "Brat Style" bikes were created out of necessity, So the HIPSTER Japanese couples could own a "Cool modified" bike...and still ride two up. If an average Japanese guy stands 5' 6" @ 135 lbs and his girlfriend is 5' 3" @ 95 lbs, they would easily fit on that seat comfy as two bugs in a rug...Now for us Americans, its a different story...when I first got my bike put together my wife wanted a ride. so me, 6' @ 170lbs and wifey at 5' 6" @ ? lbs. It was a hilarious fiasco...to say the least.
Here is a brat style bike, sitting in the brat style shop, built by the brat style guys.
Here is my personal interpretation of the brat style.
Bobbers...A quote from VonYinzer.
The bobber style of motorcycle was NOT created in Japan. It came about in America post WW2. The term "bobber" refers to the act of cutting or bobbing the fenders and body work on a stock motorcycle. Traditionally bobbers are motorcycles that came from the manufacturer with a handrail frame. Usually pre or war time American bikes.
They were built to be as light and quick as possible. Ride them to work Mon - Fri and race on the weekend.