His appearance is never completely described; the story mentions his "odd shadow" and "bright, wet, purple gaze", and the obstetrician at his birth was said to have "screamed and dropped him and tried to kill him".
Anthony's powers were present at birth, as he was able to kill the obstetrician and then, instinctively, separate his birthplace, the town of Peaksville, Ohio, from the rest of Earth moments after he was born.
However, the story does not present Anthony as malevolent or evil; he is simply a three-year-old boy with any young child's limited grasp of the world, yet with god-like powers.
Since Anthony can act immediately on any whim, those he dislikes can come to a quick and nasty end, even if he regrets it later, and no one dares suggest he undo what he has done, since the results could be worse still.
Dan receives a newly discovered Perry Como record for his birthday and wants to play it right away, but as Anthony does not like singing, the others advise him to wait until he gets home.