Each of them, especially the twins, have a very strong magnetism about them, a charisma that often lulls people into trusting or desiring them. Beautiful by choice, as they all tend to be, it can become difficult indeed to resist them. Fears and wants are their domains, often taking the forms they find in the minds of those who interest them and presenting themselves in this way. Psionics of a powerful nature, they are adept at winnowing into thoughts and minds to gain that which they seek. As with any demon, charming them is dangerous. They'll offer gifts to those they find endearing, or simply take them if they so choose. Each one is able to lose their corporeal form and become mist or fog, each can alter themselves into a myriad of animal forms. Considering them undead is incorrect, inhuman is truer. Supernatural, definitely.
Immense sexual appeal coupled with an entrancing presence, almost hypnotic voice and softly pulsing eyes often secure their targets. Those who need more incentive may find it forced on them. This breed is incredibly strong physically and harbours a fantastic stamina. They rarely sleep, if at all, but do stay hidden from the sun. Illusion is a speciality among them, and when coupled with desires, the illusion can become real, or at least a simulcrum. Magic of the darkest kind is theirs to employ, and blood gifts them with very special properties and powers over the ones from whom they consume it. If flesh, too, is taken in, it secures their ownership but does not necessarily begin the transformation into one of the Overlords' creatures. This breed tends to do things slowly, a series of bites or nibbles, but it is not necessary in the least. As in many a myth, the exchange of blood between one of these and their desired victim, however it's accomplished, will turn one fully from whatever they were before to one of the twins' kind. Perhaps this is where that myth stems from.
The transformation itself is painful and takes a few days to complete. What is mortal is burned away, almost literally in a bloodfire, and what is immortal is transfigured. The soul is lost in this changing, subsumed but not destroyed; more like a twining into the form. Even the mind is altered, and all vestiges of remaining humanity (or what have you) is stripped away. Healing is exceptionally quick, and the elder of this kind immune to many magics save those of Light. To things of Light they are highly susceptible, though it may not kill them. Rest assured, it will, most likely, chase them away... and burn in their minds as a wrong done to them forever. Which, of course, ensures their undying hatred and lust for vengeance, which can manifest in truly horrific and spectactular ways. And last throught the ages, down through generations.
Aside from these abilities, each creature has their own special, personal gift. And each one is totally and utterly loyal, without choice, to their masters. Slaves and lapdogs of the most horrendous kind... which is as the twins desire it. Resisting a command is impossible, and can only be done in that small amount of time it takes to complete the transformation. Saving a being can also only be done during the Final Altering, and then only if the one who began the Altering is wholly destroyed.