In terms of character development, how is Ahab destroyed by his obsession yet unconquered in Moby Dick?"AHAB detroyed himself through his own...

Captain Ahab is obsessed. He is a monomaniac, bent on
meting out retribution to a white whale. When we see Ahab's quest as a personal conflict
between Ahab and Nature (or God) as represented by the whale and the sea, we can argue
that Ahab gains some measure of victory in his
battle. 

Contained in Ahab's desire for revenge is also a
refusal to allow God to be the arbiter of his fate. He will choose his own
fate.

He will
fight against fate, rather than resign himself to a divine
providence.

That his fate
will be to die in his confrontation of Moby Dick does not lessen the fact that it will
be Ahab's choosing to make this confrontation. 

In this
way, Ahab does achieve some victory. It is a victory of free
will. 

In
making a choice and sticking by it, he can be seen as valiantly exercising free
will.

Ahab's will is never
conquered or diminished even as he is destroyed by his obsession with revenging himself
against Moby Dick.