Is is still a dragon if it comes from outer space?

Without proper disposal, a BMM can survive the procedure and become exposed to several dangerous diseases in a biological waste landfill.  Managing to leave this landfill and being reused for another job after disposal will spread these diseases outside closed off contaminated areas, and in Host 0’s case, release a dangerous individual into society.  Most likely, Host 0’s prolonged close contact with diseases in a biological waste landfill, specifically the solver virus and LBW, have caused it to become what it is today.  It can also be noted that because the original BMM was unregistered, it is unknown how long they lived with the solver virus before attacking others.  Which means they may have had an extended period of time to plan their takeover and perfect their abilities before revealing themself.

After its initial attack on the manor, Host 0 was able to amass a large army of solver spawn and destroy most human infrastructure on Earth in 60 days.  Thousands of accounts of this tragedy have been published and details are well-documented, so I will not go into them here.  Instead I will focus on how Host 0 was able to spread from Earth to other colonized planets.

Host 0 is known to amass living matter so it can shape itself into a mimic of another living thing.  If we accept the above theory that it’s closely connected with LBW after its time in a landfill, then it stands to reason it can absorb LBW as well — which is an interconnected network of living tissue similar to cancer and fungal growth.  By becoming part of this network, Host 0 can then gain access to anywhere where LBW is present, and nearly every colonized planet to date has at least some documented growth of LBW.  Every planet Host 0 has destroyed had documented LBW growth.

It’s most likely Host 0 absorbs into this network of living matter on one planet and is then able to recreate a clone of itself on another. So, despite the strict regulations and screenings put in place to prevent more dead worlds via space travel, Host 0 continues consuming more planets. (Out of universe note: Cyn only does this to travel vast distances between planets.  Every time she recreates herself, more of her original behavior is lost as she becomes a copy of a copy of a copy etc, so she doesn’t do this often. The solver virus does its best to approximate her and the LBW network becomes more insistent in her mind — combining to make her into the walking viral infection she is.) 

Once recreated on a planet, Host 0 will begin the same process it started on Earth — clearly finding it very effective.  It begins by immediately infecting as many people as it can with the disassembly virus, turning a number of the population into solver spawn or vampires.  It will not stop growing its makeshift army until all infrastructure built there is overrun by human or BMM based monsters.  

During this time, squads of vampires will be inclined to build their infamous ‘corpse spires’ which are large mounds of corpses the group has killed.  Their natural processes seem to associate these piles with marked territory.  However, to Host 0 these are the perfect place to amass more LBW, which thrives in piles of rotting corpses.  

With such a large amount of dead, more people will also be exposed to the solver virus which appears in LBW and rotting corpses. While most hosts of this disease will die from it and break down into LBW themselves, some survive to become true solver virus hosts like Host 0 — which will relentlessly target any and all other hosts.

As the world declines and larger growths of LBW spreads, this is when Host 0 itself makes its most well-known appearances.  It’ll toy with the remaining lives on the planet, kill other infected hosts, try to flush out every last person, and either turn them into LBW by killing and absorbing them, or solver spawn by disassembly virus infection.  No one has managed to survive a direct encounter with Host 0, though plenty of footage of incidents involving it exists.

A planet is considered ‘dead’ when everything on it has either been torn down or absorbed into LBW.  After Host 0’s rampage is complete and no natural life is left on the planet, the being itself will absorb into the masses of living matter and continue on to another planet.  It will leave behind its army to be absorbed into LBW with all infrastructure — including interplanetary travel — destroyed, marooning them on the dead world.  Complete destruction leaves behind nothing but hundreds of miles of interconnected LBW stretching over the surface of the planet.

Little lore side note from this in-universe description:

After destroying Earth, Cyn originally leaves N, V, and J to die with the rest of the vampires on the planet.  However, she began to miss tormenting them and returned with one single landing pod as their ‘savior’ disguised as Tessa.  This is the first time they see her like this and are fooled by Cyn’s disguise.  They follow her off the planet in the pod (their same one from the show) only to land on yet another dying world as their ‘Tessa’ explodes into a pile of viscera that reshapes itself into Cyn.  She punishes them all for trying to escape her and following ‘Tessa’ instead — claiming their punishment is to follow her from planet to planet killing more worlds, when the original deal was only to take Earth.  

That’s a lie, she already decided to take them with her anyway, but she likes when they believe bad situations are their fault.