Anselmium
Discovered by Anselm Magnus, Anselmium is a metal that is the bane of a Kindred's existence. When in contact with a Kindred's humanoid skin, it will disable any attempt for them to transform into their draconic form. Constant inaction and reaction to this metal is not healthy for a kindred (i.e. putting on and taking of a collar made of Anselmium in a period in between 5 hours), and could eventually kill the kindred or at the very least permanently disable their abilities to transform into dragons altogether.
Plessium
An intelligent dragon with an unknown name gave this metal to its kindred that was simply named "Plessie." Plessie showed increased abilities in both forms, seeming to be a mirror to that of Anselmium. Plessium as it is now called augments a Kindred's abilities tenfold; as in making them stronger, and in senseless feral.
Multiple Masters
Kindred can sometimes be shared with two or more dragons, each gaining a dragonstone from the other. The Kindred is granted access to both dragon clicks and two dragon clicks whenever they reach "Dragon Click" as a special feature. These kindred are most of the time feral due to the unstable relation between two dragons (unless those dragons are of the same kind).
Half-Elves
Oddly enough, a half-elf may also be entitled to become a kindred. While not a weakness or augment of detail, it is surely possible.
Drow
Drow, while they are elves, are least likely to become Kindred. Due to their dark nature, they are usually found and bred by some manor of chromatic dragons. Silver dragons may take drow, but are not that likely.
Draconic Elves
If elves and dragons are able to give birth, they may instead give birth to kindred. Kindred in this way are more rare and costly on markets, due to them inheriting their nature and not being gifted it.
Dino-Kindred
There is only a single legend where a kindred merged with a dinosaur on assumption of its master. Not much is known about the dinosaur in particular, but it has been brought out as a legend nonetheless.