Rules: Rearing A Dragon

Being an adoptive parent to a dragon is no easy task. Even good-aligned dragons have a sense of superiority and an innate yearning for freedom. Most dragons instinctively defer to older dragons of the same kind, but they tend to regard other creatures with some disdain.
Older and wiser dragons eventually learn to respect nondragons for their abilities and accomplishments, but a newly hatched wyrmling tends to regard a nondragon foster parent as a captor—or at best as a well-meaning fool. Still, it is possible for a nondragon character to forge a bond with a newly hatched wyrmling. Accomplishing this requires the use of Diplomacy or Intimidate as well as (eventually) the Handle Animal skill.
A character seeking to rear a newly hatched wyrmling must begin with a Diplomacy or Intimidate check to persuade the dragon to accept the character’s guidance; 5 or more ranks of Knowledge (arcana) gives the character a +2 bonus on the check. The character’s Diplomacy or Intimidate check is opposed by a Sense Motive check by the dragon. The dragon has a +15 racial bonus on its check. Certain other conditions, such as those mentioned on the table below, can further modify the wyrmling’s Sense Motive check.

This opposed check is rolled secretly by the DM, so that the player of the character does not immediately know the result of the check. If the wyrmling wins the opposed check, it regards the character as a captor and attempts to gain its freedom any way it can. (Most dragons, even newly hatched wyrmlings, are smart enough to forego an immediate attack on a more powerful being, and will wait for the right opportunity to escape.) No attempt by this character to rear this dragon can succeed. This opposed check cannot be retried.
If the character wins this opposed check, he or she can attempt to rear the dragon. The process takes 5 years, but once the rearing period begins, the character need only devote one day a week to the dragon’s training. Throughout the rearing period, however, the dragon must be fed and housed at a cost of 10 gp per day.
When the rearing period has run its course, the character attempts a Handle Animal check (DC 20 + the dragon’s Hit Dice at the very young stage). Only one check is made, rolled secretly by the DM. A failed check cannot be retried. If the character’s Handle Animal check fails, the dragon is not successfully reared and seeks to leave, as noted above. If the check succeeds, the character can begin to train the dragon to perform tasks.
For many characters, the ultimate purpose of rearing a dragon is to make it available to the character as a cohort. To rear a dragon for this reason, the character must have taken the Leadership feat (see page 106 of the Dungeon Master’s Guide) by the time the rearing period expires, and must have a sufficiently high Leadership score to attract the dragon as a cohort at that time (using the dragon’s Hit Dice at the very young stage as its cohort level). Also, the dragon’s alignment must not be opposed to the character’s alignment on either the law-vs.-chaos or good-vs.-evil axis (for example, a lawful good character cannot attempt to rear a chaotic evil wyrmling).