I've been looking in
Unfinished Tales, in particular the 'Narn', and came across this dimly remembered (by me) passage, when Nienor, lost in the mist, returned to Amon Ethir:
And as she climbed so the fog grew thinner, until she came at last out into the sunlight on the bare summit. Then she stepped forward and looked westward. And there right before her was the great head of Glaurung, who had even then crept up from the other side; and before she was aware her eyes looked in his eyes, and they were terrible, being filled with the fell spirit of Morgoth, his master.(My emphasis)
The fact that so large a creature can move so fast and so silently I found genuinely scary;
and then we have the emphasis that his eyes had the same spirit as his master Morgoth.
Certainly Glaurung was bred by the latter as a living weapon, as
Zigūr correctly says.
In terms of Chrysophylax the Rich, I agree with you,
Pervinca, about him being a '
slightly more moderate beast' than Glaurung and Smaug. But we need to remember that the world of
Farmer Giles of Ham is quite different from that of Middle-earth.
Giles and Chrysophylax end up haggling, as if they were in a marketplace.
Giles, not being a knight, doesn't feel any obligation to actually kill that dragon, and agreed to let him keep part of his fortune in return for defending his share against the King. This he does; and Giles ends up by becoming King of the Little Kingdom. Chrysophylax stays with the latter for a long time, to the benefit of Giles; because '
a man who has a tame dragon is naturally respected'.
What is particularly interesting is that Giles decided to give Chrysophylax his liberty, and that the dragon intended to keep their agreed pact of non-aggression. The reason given is interesting:
In his bad heart of hearts the dragon felt as kindly disposed towards Giles as a dragon can feel towards anyone. After all there was Tailbiter: his life might have easily been taken, and all his hoard too. (My emphasis)
The different world and Giles' character means that one can envisage a dragon having a kind of respect for the latter. There's also the fact that his cave and the borders of Giles' kingdom are quite distant; so there would be no obvious reason for Chrysophylax to come into conflict with him and his people in the future.