Look on the marker and see if there's a phone # you can call. Otherwise, try your leather cleaning kit. I doubt you'll get it off - permanent means permanent.
Your son is called Fruitcake? Not meaning to be offensive just saying it is unique! Most stores sell special cleaning agents for leather as it is very delicate and you can't use just anything.
The leather professionals that roam these sites like AnnieR will tell you that there is NO other way to clean leather unless you buy their kit or the world will end....
In reality, you can try WD-40 or hairspray. Test it on an inconspicuous area of the couch first.
Good Luck!