This is what happened to Eliohann...taken from pg 149 of Lockdown:
The saviors of Salem are not the witches, though they helped. The true saviors of Salem were the Children of the Dragon, as it had been seen. A child laying the dragon low. The battle occurred south of town, though tales say it was not much of a battle. As the iridescent beast flew north, the witches sought to stop it, but their petty arguments over Damon had severed their coven so greatly they could not draw the power to challenge the dragon. But the Children were fueled by the twisting of the mana, fueled by what others saw as Damon’s corruption. The dragon had not doomed them as they thought, but saved them.
Spells and spirits flew to the approaching Eliohann. The iridescent plague was rent from his skin. The mad malice could not be calmed from his mind, so his mind was pulled to its brink and beyond. The malachite beast crashed into Quarry Lake. The Children held vigil beside the steep sides of the lake and waited for the beast to rise again. They waited for the spirit to take hold of the vessel they had brought down and the light of Dunkelzahn to return to the world. The witches, unified in terror and fear, began to divide again. Some pushed to send the Children away, fueled by anger at being saved in their own land. Others saw the Children as their saviors, as hope and light personified. They sought to join the Dragon Worshippers and were welcomed with open arms. A third group thanked the Children for their actions and simply held to the Wiccan way—the course of nature, the power of the light, and the rule of three. Damon slipped from their minds, replaced by a new dragon to worry them.
The core group of believers waited by the waters for three days and nights. Their chanting was said to never waver, never cease, and in the end the dragon rose from the waters and came into their ranks. It spoke to their minds, a tale none would speak to me, but they went with it into the heart of Salem and declared their demands. They sought rights to the lands north of the sacred lake, the forest and wilds, a small section of homes, and the local high school.
Standing before a dragon and his worshippers, at the focus of a ley line of great power aligned to them and fueling their abilities, The witches had no choice but to relent. The dragon went from them, the Children thanked them, and the quiet truce of Salem was struck. A truce held in trust by the parties who made it but ignored by those who came after.
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So you can see, the big E is upright and meandering around in Salem..with a ley line attributed to dragons and a load of Children of the Dragon thinking he's the Big D reborn.
As for what Damon is up to in Boston after the lockdown, from pg 129 of Lockdown, as told to AJ via a guy named Flake:
“Yeah, Damon came to town. He’s been doing the whole\ wandering-monk thing. Kinda like you, but less nosy. I talked with
him a lot since Sakuri didn’t trust him and wanted my opinion. He said a lot of things and apologized for the actions of his dragonkin
but wouldn’t give details as to what’s going on. I don’t think he actually knows. Warned us to stay away from Salem and MIT&T...Actually, Damon had a following. They kept their distance, and I think most of them stayed out of sight to not spook us, but I
saw them join up with him on his way south."
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Sounds to me like Damon feels used by Celeydr and Eliohann....
As for Cereius being in control of Eliohann's body, I don't think so because of this (from pg 213 of Lockdown):
A creation full of the purest hatred for both of its parents, this creature wants nothing short of the destruction of both parents in every form and place. From the annihilation of the head cases in Boston to the death of Eliohann, it wants nothing left of the codes that spawned it and has no care for its brothers and sisters beyond its ability to use them before discarding their deleted husks
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From that I get the feeling that if Cereius were to find itself within Eliohann's body, it would do everything to destroy that body...not live in it.
And here's the thing Miles Lanier said in Market Panic that got me thinking this is Deus or something like it, in a dragon body (pg 125 Market Panic):
I have had no other place to put this, so it will go here and I will simply hope that he finds my sentiment here
someday. Celedyr, I am sorry for your loss. Eliohann was in his day a bright star in the gloomy murk of draconic society. I truly hope that the end result of your efforts is as you intended. You had the best of intentions. I have already felt the loss of Cerberus in my efforts but hope that the mind and body can once again unite and glow like a supernova. That said I also apologize for any part I may need to take in assuring that an abomination of the worst sort does not find its way out of the Boston quarantine. You and I both know there are worse things within those walls than the hordes of raging head cases. If you get this message and desire to contact me, the Soulkeeper knows how to find me. Sincerely, Miles
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That's what makes me think that whatever is driving around that dragon's body..it might not be Eliohann....