Of course, if Harry's the original Merlin, then according to another theory he's his own grandpa. That theory being of course that the journals in Eb's office are not only from master to student but from grandfather/father to son.
Going only by the Dresden Files, Merlin founded the white council, wrote all the laws, and was custodian of one sword. Harry founded the gray council, will break all the laws, is custodian of two swords.
Oh, and he's also a guide and mentor for troubled magical youths.