Dragons play small but important roles in the history of Cerilia. They are hard to find but have resulted in major historical events. Many have died but a few remain. Little has been defined about them so I was wondering how people have placed them in their campaigns.

To quote the BRCS:

Cerilian dragons are among the most ancient inhabitants of the continent, predating even elves and dwarves ....

All Cerilian dragons are accomplished spellcasters. They cast spells as sorcerers, and they have a preference for spells from the schools of abjuration, conjuration, divination and transmutation. They can also access spells from the clerical domains of healing, knowledge, and protection.
But there is no record of dragons being divided like the Sie were (into Seelie and Sidhelien). Presumably they have the permanent connection to mebhaighl like elves do, so they can cast realm spells. However, can they be regents at all? If so, do they need to be blooded, especially given their clerical magics? Either way, can you bloodtheft from a dragon? Is it a new bloodline?

IMC the party encountered two dragons in the Shadow World who initially disguised themselves as Sie. Does anyone used Shadow Dragons or Dragons who use shadow magic or Seeming? Does anyone give the Cerilian dragons any connection to the Shadow World?

I realise that their rarity and power makes dragons something that DMs can play around with a lot, but I am curious what sort of background history/biology people have placed on them.

Sorontar