According to Dad, my brother Colin would march around the house (when we were toddlers) declaring "I'm first, I'm first!" I'd follow close behind claiming 'I'm first, I'm first.' That pretty much sums up our sibling dynamic, though now I can spot his antics.
And while I'm mentioning brothers, the littlest one (and yet the tallest), Ethan, has been spreading mental health awareness through his work Dork Dancing. Pretty sure that makes him the coolest, as well.