There was not much work to be got out of Duny. He was always off and away… (1.3)
Here's Ged as a child (he was called Duny back then). We already know that he's proud and easy to anger, and now we see that he would rather play than work. In other words, he's kind of an ordinary kid.
They knew him and did him honor by the Prince's order and their own will, for ten years ago Ogion had saved the city from earthquake… (2.55)
Ogion might be the most powerful wizard on Gont, and since he's the most powerful wizard on Gont, he has some responsibilities to the people and the island. Most of the time that means that he visits people and heals the sick, but here we learn that he's also cast really powerful spells that have helped everyone.
To check the ungoverned spell and drive off the shadow from Ged, Nemmerle had spent all his power, and with it his bodily strength was gone. He lay dying. (4.61)
Nemmerle is like the best school principal ever – not only does he make Ged feel comfortable, but he also sacrifices his life so Ged can survive. Now, you might think that's a little excessive of Nemmerle, but, if you think about it, Nemmerle is just fulfilling his duty as caretaker of the students. That's an A+ caretaker, if we've ever seen one.
It was not his own life that he bargained for. One mastery, and only one, could he hold over the dragon. He set hope aside and did what he must do (5.85)
Perhaps inspired by Nemmerle – who carried out his duty even though it came with a price – Ged does something really heroic here: the dragon Yevaud has promised to help him with his personal problem (the shadow monster), but Ged has a particular duty to the people of Low Torning. Ged might have been a selfish kid (running off to play rather than, say, working with his dad), but he seems heroic and selfless now.
He went to the Sea-House of Serd, where travellers and merchants ate together of good fare provided by the township, and might sleep in the long raftered hall: such is the hospitality of the thriving islands of the Inmost Sea. (6.19)
We often think of duty in this book as things you must do that are related to your job – if you're the wizard of a village, then you're supposed to heal the village-people, etc. But here's an example of something that we might call a duty towards strangers and guests: the town feeds people who pass through because there's a general responsibility to be hospitable hosts. This contrasts pretty strongly with how Serret treats Ged when he's her guest at the Court of the Terrenon.
"Master, I go hunting." (7.118)
In this short sentence, Ged expresses two duties: 1) he has to stop the shadow from hurting more people, and the best way he can do that is to hunt the shadow; and 2) he has a duty to Ogion, his master, who's his real teacher and the one person who always gives him good advice.
Ged made the charm well and honestly, working on it all that night and the next day, omitting nothing, sure and patient, though all the while his mind was strained with fear […] (8.5)
Remember how in Chapter 5 Ged was so overwhelmed by his fear of the shadow that he didn't think he could do his duty for the town of Low Torning? Now, although he's still afraid of the shadow, he can concentrate well enough to do his duty by concentrating on casting this charm well.
Had Ged been free of what was laid on him he would gladly have stayed there a week or a month to sing them what he knew, that the great songs might be known on a new isle. But he was not free, and the next morning he set sail, going straight south over the wide seas of the Reach. (9.4)
This is certainly a radical contrast with Ged from the first chapter. If Ged in the first chapter wanted to do something, he did it, even if it meant getting beaten by his father. But by the end of the book, Ged can separate out his desires from his duties.
Growing weary of old men who nagged him, he said, "I am yours, by parentage and custom and by duty undertaken towards you. I am your wizard. But it is time you recalled that, though I am a servant, I am not your servant. When I am free to come back I will come back: till then farewell." (9.83)
Vetch has a job to do – he's the wizard for Iffish. But he's also a wizard for this friend, Ged, and for the world, and for the Balance itself. Duty isn't just about a job – it could be about responsibility towards the whole darn world.