Rlyeh

Primordial.

A word oft uttered when describing this hulking, sea-dwelling monstrosity. In truth, Rlyeh is not a natural born creature; rather, he is merely a mortal shell for something so very other. The truth of this is evident in the unease he provokes in other living beings, best described as a skittering feeling beneath their scales and an instinctive drive to get away as far as possible. No one can pinpoint if there is one sole aspect that elicits this feeling, responses varying.

Some are unnerved by never hearing him speak, only vocalizing through raspy, guttural growls. Many claim his aggressive body language, that of a creature tensed to strike. Other dragons cite his eyes as a source of anxiety, even when they are scarcely visible beneath the bedraggled kelp that persistently clings to his body. The abyss stares back is a phrase that definitely applies.

Despite this, there have been zero reported incidents regarding attacking other dragons. Perhaps it is largely due to them giving him a wide berth... or, perhaps, he is crafty enough to cover up evidence by dragging it back to the depths.