It is reasonable to assume that Nora is not the first dragon, though she may well be among the first generation -- or a relatively early generation anyway.
She refers here to "brothers and sisters," and Nora has not thus far appeared to use those terms in a non-familial way (as, for instance, the Basitins may use fraternal terms to describe other Basitins who are not relatives).
Tom's mentioned on the forums that Dragons, when they spend time around the other races, tend to be venerated as sages and historians:
Tom wrote:There are very few dragons in the world. However, they have an unlimited lifespan. In other words, so long as nothing kills them, they are capable of living forever. Dragons also never forget anything they see or hear. They can recall memories of any day they've experienced without flaw. Due to these two attributes, dragons are often referred to as "living libraries." Their minds hold huge volume of information, and they have a natural urge to share it with others. Dragons are often found in the company of Human, Keidran, or Basitin historians.
Nora may be among the oldest that still interact with the races, though; at a certain point, your experience and power is such that "younger" races aren't very interesting anymore. And, of course, they're all going to die anyway. Better to pursue your own interests in peace.
Personal characteristics would become exaggerated over time, something we certainly see in Nora. Dragons who still have an interest in the races would logically be found in the company of historians, who would flatter them and hang on their every word, and, while Reni's role as comedic relief somewhat exempts her from the flaw, it would appear that dragons are fairly vain and appreciate the attention. And, since there's prestige in age and power (and since we certainly don't know how dragons reproduce), it'd make sense for dragons to claim lineage from the oldest and most powerful they can link themselves to -- however tenuously -- to borrow some of the prestige of those forebears.
As creatures
of magic, I'm not actually certain that a person could derive black mana from draining a dragon. Black mana is the magic of life. Is that what animates dragons? Nobody other than a dragon (Nora) seemed to feel terribly ill effects from the disruption of magic on the Basidian Isle (though our sample size is awfully small in both cases) and the King's condition improved dramatically (as magic was responsible for at least part of it). So the Tower explosion presumably didn't disrupt life energies on any kind of non-immediate scale, but it still dramatically weakened Nora as it disrupted magical energies on a moderate scale. (I'm quite curious what it did to the fields of subtleflowers too.)
Disrupting magic probably isn't much of a tool of anything but last resort for the Templar -- their primary skill is as battlemages, and Human magic is the talent and edge they have over the Keidran and Basitins alike. It'd have to be a pretty bad situation to say "Okay, I don't want anybody to have magic" when
you're the side that possesses it in the greatest abundance and can wield it to the best effect. If they were being attacked en-masse by dragons, that's possibly an option, but the Human kingdom appears to venerate dragons and the Templar have a very positive relationship with them (you can point at Trace and Nora, but it predates Trace significantly, since he
met Nora at the Templar academy). I'm not sure what circumstances would make the Templar interested in killing dragons. Even Trace, the guy who wanted to kill everybody, didn't seem interested at all in killing dragons.