Demi is the name of the flight that succeeded Ozork Flight and continued to live in Ozork's Eerie. Dragon flights change names very rarely, and there is a complex set of conditions that must be met for the flight to accept such a change.
In the case of Ozork to Demi, the key difference was the introduction of human DNA. Nearly every dragon in Demi-Flight is at least 5% human, while most are various hybrids up to one quarter. The addition of human-DNA allows them to retain most of their dragon abilities, while continuing to reproduce as Fallen Dragons.
The Dragons of Demi Flight live much shorter lifespans, with most averaging only 100 years; a few reach 150, depending on their quantity of human DNA. The elders of the flight are all dragon-sorcerers surviving from Ozork, whereof are very few remaining.
The cost of incorporating human DNA is that Demi's dragons lose the ability to take any form besides dragon (despite being part-human). They also do not grow as large or as fast as pure dragons. While this makes them very capable warriors, they lack the discipline and training offered by a more traditional flight.