In chapter nine of Grendel, what ironies occur?

In chapter nine of Gardner's Grendel,
irony is present in the interactions between Grendel and the
priests:

readability="10">

"Great spirit," the chief of the priests wails,
"ghostly Destroyer, defend the people of Scyld and kill their enemy, the terrible
world-rim-walker
[Grendel]!"

The priest prays
for Grendel's destruction while Grendel listens and waits for someone to come kill him,
which is ironic.  But the irony increases when Grendel poses as the Destroyer
himself. 

At midnight, with Grendel sitting in the ring of
the gods, Ork comes and asks who is there.  Grendel
replies:

"It
is I," I say.  "The
Destroyer."

Grendel, the
nihilist and atheist, poses as the god the priests pray to for Grendel's destruction. 
That is ironic.

The irony is heightened still further when
Ork sees his visitation or vision as
confirmation that he is correct in his theories and beliefs.  Grendel, the being who
detests the pattern-making of humans, laughingly contributes to the confirmation of the
patterns envisioned by Ork.