Dragon Mount
A dragon sovereign has a mystic bond with youthful true dragon, a bond that guarantees the dragons loyalty to the sovereign (as long as it is treated with respect), and allows the dragon sovereign to tap into some of the dragon’s arcane power. A character that begins on the dragon sovereign mythic path is approached by a dragon of his choice as a prospective bonded mount within 30 days of obtaining a sovereign relic. Once approached, the character is then considered a 1st tier dragon sovereign and gains a dragon mount. He is assumed to have already bonded with the dragon. The bond causes the dragon to grow slightly in size, and drives it to gain power as its dragon sovereign gains experience, rather than as it gains age categories. Many of a dragon’s normal powers (spell-like abilities, spellcasting, unlimited breath weapon use) are either suspended or modified as the arcane power that drives them is used to fuel the bond between dragon sovereign and dragon mount. This bond, once forged, ends only if both sovereign and dragon decide to end it, or if one is killed and not resurrected in a timely fashion.
Most true dragons are unwilling to undergo this bond (though there is always one that will do so and is able to find a dragon sovereign without a dragon mount). For good dragons this is often done to aid good-aligned dragon sovereigns in facing the evils of the world. In some cases it is part of ancient pacts dating back centuries or even millennia that dictate service of a set number of dragons of a given bloodline. Even among neutral and evil dragons however, there are always a few who seek out such bonds willingly.
The reason for this is a desire for power, and an ability to take a long view. A dragon mount bonded to a dragon sovereign grows in size and power as the dragon sovereign gains experience. The payoff comes when the dragon sovereign dies, though dragon sovereigns often live as long as their mounts, due to their mythic nature. At first, if the dragon sovereign dies, the dragon mount simply must survive as an underpowered dragon, but after a year and a day from its sovereign’s death if it has no not bonded with a new dragon sovereign, the dragon begins to gain the full power of a normal dragon of its size (or the oldest category in its size class, to a maximum age category of very old).
Consider a red dragon wyrmling. It is Small, and won’t reach Large size for roughly 20 years. It won’t be Huge for 45 years, and Gargantuan size is at least 4 centuries off. But if that red serves as a dragon mount, it becomes Large immediately, and stands a fair chance to become Gargantuan within a few years. If it survives its dragon sovereign’s loss, the red dragon will