Who is Mr. Donner in Flowers for Algernon? What was he doing for Charlie and why was he doing this?

Mr. Donner is Charlie's boss at the bakery; he had been best friends with Charlie's Uncle Herman. Uncle Herman used to watch out for Charlie's welfare, and had brought Charlie to the bakery long ago, asking Mr. Donner to let him work there and to look after him. Uncle Herman had died a couple of years after bringing Charlie to Mr. Donner, and it was fortunate for Charlie that Uncle Herman had enlisted his good friend's help on Charlie's behalf. After Uncle Herman died, Charlie's mother had institutionalized her mentally challenged son, committing him to the Warren home.  Remembering his promise to Herman, Mr. Donner arranged to have Charlie released on outside work placement, giving him a job and finding him a place to live.

Charlie started working for Mr. Donner when he was about fifteen years old; he is almost thirty-three now, and the kind man has been looking out for him for seventeen years. Because of his mental challenges, Charlie has not moved up in the company at all; his main tasks are cleaning up and making deliveries. Although the bakery business is not currently doing well, Mr. Donner reassures Charlie that he will never have to go back to the Warren home, because no matter what, because of the promise Mr. Donner made to his uncle, Charlie will have a job at the bakery for the rest of his life.