Age: Unable to be told for sure, but thought to be fairly ancient.
Gender: Female
Appearance: Mortuus is an undead dragon, and as such, does not come too appealing to the eye. She would have looked like a generic dragon if it wasn't for her torn flesh, revealed ribcage, and bone-tipped tail. She has wings, but they are torn to such an extent that they can no longer hold her in flight. Her stretched skin, what little of it she has left, carries a green tint, while the muscle under is a sort of dull red. Most of her skeleton, including the enamel of her teeth, is in tact. Fangs extend outward and can retract to grab on and pull on flesh, similar to what a snake can do. She has the ability to create diseased zombie minions, and she can also possess a lesser being if their will is weak.
On the subject of her gut, one would think Mortuus is nothing but rotting flesh and entrails, when, really, what lies in her center is the source of her unlife. It is what keeps her limbs animated without muscle to support them, what keeps her mind in tact. It is a strong orb of energy that came into existence a few hundred years after her world began. She found it, and it consumed her.
Now, she walks, unable to rid herself of it, unable to understand why it had chosen her those long years ago.

In the old, mass continent of Pangaea, there were dragons. For most, it would be hard to believe, though the fact stands. With bones made of keratin and cartilage that dissolved all too quickly to leave a fossil trace, there never was any good enough reason for humans to believe that, indeed, these beasts lived, breathed, and ate, just like any other beast of the land during that time.
Wind back to this time and center on one green dragon in particular. Let us call her Mortuus. She was fearsome, to the top of her game, and fully matured. Today, she is hunting, soaring above the great plains of between what would soon be the rift between South and North America. Today, she would be met with the strangest phenomenon known to man, even now. A storm was brewing, and as she flew over a great, dark chasm, spanning miles over the surface, a wind too strong for her massive wings to withstand would overtake her and push her into the chasm.
Skip forward a couple million years.
Societies of humans have been established. Buildings became complex, humans created technology. Professions were established. One human would choose to be an archeologist, and this certain archeologist would choose to go to the border of South America to dig. He would find the greatest discovery of humankind. He had found a dragon.
Reverse time again, but only a few hundred years. The black plague swept Europe, and there was talk of a horrible beast roaming the land.
One year after the bubonic plague ended, there was a horrible earthquake in North Italy. Talk of the beast was dismissed as superstition.
Cue back to the modern day, to the archeologist. He is dead. The world is dying. There is a new plague. There is a monster lurking, hungry.
Terra, in a sense, discovers this being, and takes it from the modern world to the Multiverse.