In this storied border battle, there appears to be some common ground. And he wears No. 4. “It’s the one thing we agree on,” a purple-clad Vikings fan quipped to her neighbor, who was sporting a Packers jersey, as they waited to catch a glimpse of Hall of Fame quarterback Brett Favre. Hundreds of diehard Favre fanatics flooded Ridgedale Mall in Minnetonka on Saturday to collect autographs on helmets, posters and — in at least one case — their own skin. Though he made his career leading the Packers, Favre played his final two seasons with the Vikings. For some cheeseheads, it’s the only reason they’ll ever don purple. Families split by the rivalry bonded over his legacy. “Every holiday, every Sunday, it was Brett,” said Roxanne Lindquist, of Maple Grove. Her 9-year-old son, Calvin, didn’t have to choose sides. Grandma made him a one-of-a-kind jersey that stitched Favre’s uniforms together. Purple and green, one No. 4.Liz sawyer