They say that when the pupil is ready, the master will appear. Ducard prefers to let things work a little differently. When the pupil is beaten down and disoriented, he is easier to teach. If he is ready, then what is the point?
This Wayne is brutal as a caged animal, but Ducard sees the fear underneath the cruelty. Fear makes men cruel. Always, Ducard worries, a lack of fear will make him kind. That is why he will replace Wayne's weakening, paralyzing fear with a focused, refined fear. A fear that gives strength.
Ducard fears compassion. He knows this about himself, but counts it as a strength. Compassion will betray a man faster than any outside enemies.
Ducard himself was wooed in a far less gentle way. He had been drinking himself to death, slowly, methodically, first drinking away his job, his friends, and finally his health. His predecessor found him in the dark of an alley and punched him in the face eradicate that final sliver of consciousness and then . . .
Then years locked in a cage while he dried out and grew strong and rebellious. Learned to hate his captors enough to dream of killing them. Learned that killing them was what they wanted all along. Learned to kill his predecessor and then become him. It is an old story.
He wonders if this Wayne will kill him, but does not dwell on it. Ducard detects, or thinks he does, a thread of weakness, blustering boyishness never quite killed even by Wayne's wholesale embrace of the dark. Bruce Wayne will be the finest tool ever put into his hand, a scythe of destruction, but not a friend.
You have to hate a man a little, to pick and tear at his defenses as Ducard does. Early on it becomes clear how Wayne survived his years of wandering; he skates through life on the surface, even at the very bottom, like an insect on a scummy pond, somehow unaware of the monsters beneath. Or aware and uncaring. Ducard tries to force him to open himself up to everything around him, to become fear.
Once he learns how, Wayne is frighteningly good at it. Ducard leaves him with a few weaknesses. Because if he made Bruce Wayne everything he could be, he would be better than Ducard. This is not what Ducard was taught. He was taught to make each of his soldiers the best. If they are good enough to kill him, then it was his time. Ducard does not want it to be his time.
Later, he will remember that you can be killed by a man's weaknesses as easily as his strength. Before he dies, Ducard will remember that there is no cheating fate. And his last hope will be that Bruce Wayne truly was his successor; that he will pick up the reins of The League of Shadows. Someone will.