The Adalids were a proud race of pathogens who dwelled in the blue tunnels of other creatures. They always made sure to give back more than they took. They were path keepers and never allowed the Easedis to roam their waters unobserved; always careful to notify their host's defenses when the presence of such were felt. Sometimes even assisting in the clean up. And they were a very old species, as well as seasoned travelers. Some would argue they were fortunate to find hosts to take them around the aser (universe) where they soon found rights of passage to other, more complex, hosts. That is how they came to dwell on Herat (Earth). Their new host was very clean and well preserved for many generations and the Adalids were a happy species. For many cycles they dwelled in a veritable blissful peace in the crisp, blue waters of the Hasmun (Humans). Soon they became a recognized part of the scapeland and were always welcome wherever the blueness led them. Some even joined their lifelines to the Adalids and made new intentions. Improvements to the tunnels followed and all was well. 

The Adalids were very thorough filters that thrived on fatty acids while emitting proteins and carbohydrates in return. Their major metropolitan centers were always close to reservoirs of slow moving particulate, most of the Adalid always found clinging to the walls of these large structures gathering all the nutrients they would need. 

These raw particulate would be mixed with Adalid juices and ferried through the blue tunnels to their metropolitan areas to be processed and everyone could feed. They always fed in cycles. Most of the Adalids existence was chemically compounded and they were there to observe every trade. 

Once the proper chemical balances were achieved they'd gather up the excess and store it in fatty tissue for future composition. The Adalids, themselves, were quite harmless, unless you happen to be an Easedis passing through. The Adalids used the nutrients derived from human particulate and their own bodies consumed such nutrients needed and expended gas and liquids in the exchange as waste. The liquids were useful in lubricating the tunnels through which the gas would travel back to the large reservoirs which helped to keep the particulate slowly flowing. It was an extremely efficient synthesis of chemistry which rarely ever failed to keep the humans thriving. 

And there were a lot of Adalids in every hasmun, we're talking trillions scattered around the hasmuns territory but primarily around its mid section. In that trillions of Adalids there was one...oh yeah...there's always one, who was special in ways he didn't realize. Special, in this case, had to be an understatement. There were lot's of special Adalids, some even argued that all Adalids were special, but none like this Adalid. He was a mutant Adalid, for one thing, and there were many of those as well, but none like this young Adalid had ever arisen with this kind of special. He was special special. Especially around his head. 

His name was Nod and he had an unusually large head for an Adalid. In some ways this aided Nod's life such that he didn't have to attend the ceremonial journeys every cycle to the big basins to gather chemicals. It was always a long journey and returning loaded down with extra chemicals was always hard work. But Nod, due to the size of his head, was exempted from this ceremony because many of the blue tunnels were small and necessitated an Adalid contort into all kinds of funny looking shapes to pass through them. Naturally, the one body part of an Adalid that was contortion resistant was their head. So one doesn't require much imagination to see why Nod wasn't included in these ceremonies. The one and only and first time he was invited he got stuck and held up the entire procession while they figured out a way to get him free. 

Another thing about the Adalids that very few even know is how drastically participation in those ceremonies reduces the lifespan of an Adalid. Most ever lived long enough to make more than three such journeys. Though it was not something the Adalid liked to talk about, everyone knew the ceremonies were the culprit. No one knew exactly what it was about those ceremonies that so reduced their life cycles but they knew by the time they set out on their third such journey they were probably not going to make it home. 

And the strangest thing about all of this is it never seemed to occur to anyone not to go on that third and final trek. It was like something caused that thought to just evaporate before an Adalid could follow it out to it's most reasonable conclusion. Just limit Adalid's participation in the ceremony to only two. That would have made the most sense. 

And it isn't like it was vitally important an Adalid make that third journey. Since they never made it back, all the chemicals they were carrying were lost anyway once they expired. There was nothing anyone could do because everyone was already loaded to capacity and there was simply no room to retain the chemicals being lost. 

Another thing the Adalid hadn't considered was the effect these lost chemicals were having on their host. Especially if they were lost outside the parameters of the basin from whence they'd been collected. Their chemistry was what we call abrasive on any biological surface outside the basin. This was a very important piece of the puzzle that Nod began to assemble during his life span within the colony. Since he had nothing to do but watch and observe he spent many long hours tracing every single move an Adalid made throughout their existence. 

And Nod had a very large head containing a mutational agent that made him special special. But we'll get to that in a moment.