Hello again to those who recognize me! I'm rather honored, actually...
I like to imagine Bowser Jr as the 8th and youngest Koopa Kid. Because of his remarkable resemblence to his father, I feel Bowser must have automatically latched onto Jr as his favorite child (cause, let's face it, Bowser's not gonna be an ideal dad anyway, so why wouldn't he have a favorite?).
I think it'd be really fun to think up a story concerning the other seven reacting to this newfound favoritism.