See The Only One Part 1 for the beginning of the story.
Then Donald decides to get penguins. He keeps them in the basement of his mansion. He gets experts to create and ice pond and a pool of cold water with fresh herring. It's temperature controlled and regulated.
Donald gets the penguins on an exotic animal exchange. He calls the penguins Peg and Pete. They walk hand and fin with Donald who is an old man now. Sometimes he'll go swimming or ice skating with them and they get along real well.
At least Donald found the answer to life's problems. It's the satisfaction of finding the perfect friends.