And look! It has grown wings! It must be close to maturing.
Young dragons are relatively defenseless. They are born with relatively soft scales, which are shed and replaced with harder ones as the hatchling matures. Once a hatchling’s wings grow in, it marks the beginning of maturation. At this point they are often capable of hunting on their own and are usually left alone by their mother.
This young male was just sitting about one day, minding his own business, when an absolutely terrifying-looking wizard appeared before him. The man etched a few runes around the startled young dragon, leaving the poor hatchling to assume the worst was about to happen--but then the man simply bopped him in the nose with a chunk of ice, giggling all the while.
"Boop! You're frozen!"
And then he ran off cackling.
The cruel irony of the man's humor didn't set in until many years later. The tiny black dragon now hates both wizards and stupid jokes with a passion, and will vigorously bite the ankles of any mage or unfunny person he encounters.