I have three flavors of redhead friends on that score:
Type 1: Will kick the offending individual's ass as a reminder that having no soul doesn't mean you don't have a body or emotions. (2 friends.)
Type 2: Will cry and run back to their friends, including myself, who will then find the offending individual and kick his ass for them. (3.5 Freinds, the point five is because one of them would just cry more if we got violent over it and we know that.)
Type 3: The last type will taunt them back saying something like "Your soul measuring equipment is faulty, or you would have realized that ONLY gingers actually have souls, do you know how you can tell? Only redheads can do magic." (1 Friend, coincidentally the one who's not a natural red...)