I have 5 indian runner ducks, one of them is drake I incubated from an egg. That one is the largest and became the leader of the flock. I have had it for around 3 weeks, before I managed to buy additional ducks, so he could bond with them instead of me. He did that in just a day. After that, he almost completely ignored my presence for a while, walking around with his new friends. Then, he started following me around again as he saw me, leading the flock with him. As he grew more mature, he changed a bit, but never stopped following me. He was never happy if I carried him in my hands and now when he's already mature, that didn't change a bit. A few weeks ago, he climbed into my lap when I was sitting on the grass, and I'm quite sure he tried to hump my leg, because there was also some biting involved and some neck twisting around my arm.

He did not mind being in my lap that time, I even think he liked it.

That strange thing didn't happen again after that. I can pick him up, but he clearly shows he doesn't like it by lowering his head and even biting (not aggressively, more like annoyed kind of bites) when I release him.
He will come eating out of my hand any time. I have managed to introduce him to other people soon, especially children, so he gladly eats from their palms as well. None of my other ducks will do that, even I have problems when I try hand feeding them. So far 2 drakes will eat from my hands, and one of the hens did a few nibbles at one point few days ago, two hens are still far away from it.
I am thinking about raising a few more ducks from the eggs I get from the three hens I have now. They will become more imprinted on humans that way and will hopefully even tolerate being held if necessary.