Well I feel I'm a bit late to the show, but here is my initial submission for a Steel/Ghost 'Scoutmon'.
Some kind of living (or rather non-living) sentinel, scouting, probe being. Inspired largely by the sentinels from the 'Matrix', the 'Dementors' from 'Harry Potter', even 'Syndrome's' Robot from the 'Incredibles' and other out worldly creatures of the deep and/or outer space, lol. I realize it is actually not dissimilar to something
Skyshroud postered a few pages back. As not to discredit of disrespect him in any way.
BackStory:
There have only ever been a few dozen sightings of these out worldly beings every recorded in history. Mostly shrouded in mystery and secrecy. Further more the majority of these sightings have occurred in only the most remote areas and harshest of climates on earth.
Out in the vastness of deserts, high atop blistering mountain ranges, down in the deep dark depths of the oceans abyss, in under ground mines, tombs, during natural disasters and even on the outer rims of earths atmosphere and the Moon itself!
Almost all accounts have run parallel with near death and out of body experiences and are thus all vague and unclear. Yet strangely a lot of details and similarities remain the same and re-occurring. Descriptions of an ominous presence, a stillness or timeliness, accompanied with unexpected sense of reassurance and calm is retold again and again. All those that have been witness say they are "forever changed" by the experience and the one thing that remains is a memory burn of that "piercing, penetrating, glowing red stare".
These accounts can neither be confirmed nor denied. No actually proof of these creatures exists other the the impossible circumstances on which they evolve from. That along with the miraculous and unexplainable survival of those witness, who would have been left for dead other wise.
Much speculation is made of the mere existence of such beings, let along their Origins. Yet of course there are many theories and stories to explain just that. Among them there are thoughts that they are Spirit beings. Not entirely living, but not soulless vessels either. Perhaps not even of this world. It's suggested they my be creatures from another plain, like an alternate dimension from our own or messengers or carriers from the after life. Some believe they might even be more extraterrestrial then that.....