In Asar we have the embodiment of the god of our fathers, the since-deposed ruler of a kingdom that predates our birth. He is the king of a Golden Age that lives solely in the memories of the aged. As such we can endow him with the wisdom and introspection of the ancient of years, the passive intelligence of the father of our father, the benevolent but impotent role of a kindly former head-of-state.
His impotence in this world is plainly communicated to us in the myth of the Sorrows of Isis. When Suti (Set) tore Asar asunder and scattered his fourteen pieces to the far reaches of the world, the one piece that Asar's wife, Ast (Isis) was unable to locate was his phallus. This she had to fashion from wood herself in order to impregnate herself with their child, Horus.
But in the underworld, Asar is not at all impotent; rather, he is the explorer who first discovered and revealed the intricacies of the nether world, and now leads those who find themselves in that dark realm through the many vaults and chambers to the afterworld. When one dies, one is completely removed from the present, dwelling for evermore in the increasingly dim past. And in that shadow realm, everything that ever WAS, IS. Thus Asar rules there forever.