I know that there is a Dragonrider class by Super Genius Games; I have it. However, those dragons, while "party legal" are nerfed. They are animal companions, and not the "real" dragons based on the Bestiary.
Another option for a character to get a mount, such as a dragon, is by getting a cohort through the Leadership feat.
What I was thinking is coming up with a Cavalier feat that instead kind of merges the two. Or rather, instead of having the mount as a Druid's Animal Companion, that the dragon is based on the Cavalier's level and the character's total level. What I have in mind is total Hit Dice of dragon = (1/2 character level + full Cavalier level).
That is only a part of the situation, as that in itself is easy just by glancing at the character. The sheet would not need to track anything. The next part of it is to pick a dragon type, and have it effectively bootstrap that appropriate dragon age/size and all of its abilities while it is within a certain Hit Die range. In effect, as you level up it gets bigger and tougher. A level 20 Cavalier would have a 30 HD dragon. (I am aware that dragons normally get bigger by aging, but this is sort of a soul-bond thing, and might be how dragons appear in the first place, those found alone later perhaps outlived their Cavalier).
Is it even possible to do this? So, to summarize:
Feat that requires cavalier levels (yes, easy)
it disables the cavalier mount ability
instead replaces it with a dragon that levels up, based on its hit dice, which are (Full Cavalier levels + 1/2 character levels).
I might have it require a few levels in Cavalier so people don't just take toe one level in Cavalier to qualify for the feat.
Another option for a character to get a mount, such as a dragon, is by getting a cohort through the Leadership feat.
What I was thinking is coming up with a Cavalier feat that instead kind of merges the two. Or rather, instead of having the mount as a Druid's Animal Companion, that the dragon is based on the Cavalier's level and the character's total level. What I have in mind is total Hit Dice of dragon = (1/2 character level + full Cavalier level).
That is only a part of the situation, as that in itself is easy just by glancing at the character. The sheet would not need to track anything. The next part of it is to pick a dragon type, and have it effectively bootstrap that appropriate dragon age/size and all of its abilities while it is within a certain Hit Die range. In effect, as you level up it gets bigger and tougher. A level 20 Cavalier would have a 30 HD dragon. (I am aware that dragons normally get bigger by aging, but this is sort of a soul-bond thing, and might be how dragons appear in the first place, those found alone later perhaps outlived their Cavalier).
Is it even possible to do this? So, to summarize:
Feat that requires cavalier levels (yes, easy)
it disables the cavalier mount ability
instead replaces it with a dragon that levels up, based on its hit dice, which are (Full Cavalier levels + 1/2 character levels).
I might have it require a few levels in Cavalier so people don't just take toe one level in Cavalier to qualify for the feat.