"Dogwalker" is a cyberpunk novelette by Orson Scott Card. It appeared in Isaac Asimov's Science Fiction Magazine in 1989, and was subsequently included in Card's collection Maps in a Mirror.

Plot

Due to a childhood accident in which he was shot by a stray bullet while sleeping, the story's narrator has had 60% of his brain replaced with artificial computer "goo". His thyroid glands no longer functions, so his body has ceased to develop, and he has never grown out of the body of a child. His computer brain gives rise to autistic behavior, and others see him as more machine than human. It has also made him a computer hacking savant, able to memorize or guess extremely long passwords after meeting their owner once. With the help of a man he knows only as "Dogwalker", he profits from his skills in the criminal underground. They try their biggest score to date, guessing the password of a wealthy corporate executive. The savant poses as a dog walker to gain entrance to his house, and successfully guesses the password. However, the executive was so paranoid that he always entered an incorrectly password first before entering the correct password. When Dogwalker uses the correct password on the first attempt, he is discovered. The savant is kidnapped and forced to give away all of their proceeds in return for Dogwalker's life. Dogwalker returns, but he has had his brain replaced by the computer "goo". The savant cares for Dogwalker and plots revenge.