It had protested, and thus it was demoted and isolated. For a species that relied on regular interconnection, the isolation became to it what the Doctor might call 'a mixed blessing.' Had the Doctor ever had the opportunity to analyze its unique situation.
It had protested, believing the humans might be best observed in their natural habitat, and not this protected enclosure. The effects of their meddling seemed at best artificial, and at worst, completely counterproductive. But the Consensus had been to proceed as planned, and for its outspokenness, it found itself demoted to assisting the one human allowed to know their secrets. Assistant to a tool, and no more. Even during the regular adjustments, it was kept out of center.
The adjustments became both onerous and necessary to its survival. Connected to the Machine and thus each other, they became one song, one purpose, a state natural and soothing to their species. At the same time, its isolation was emphasized in the reluctance with which it was welcomed and the swiftness with which it was cut free.
But fringes have their benefits.
Freed by the situation to conduct its own observations, it began to notice things about the humans overlooked by the Consensus, and what's more, it was able to keep these conclusions to itself.
The Doctor was ever a sterling source of information. For a time, it merely observed, watching and learning as the Doctor created lives for the humans. It began to see the purpose of these 'memories', so vital to this biologically simple, yet intellectually complex species called Humans. Controlling the access to the Storage, it had only the power to provide what the Doctor required essences of memory, distilled and purified, contained in a liquid for which the humans had no name and no knowledge, a product of technology so advanced, the sheer concept lay beyond the scope of explanation to humans.
So it watched, and it learned.
Mix the liquids, adjust the environment, and alter the man, it made no difference. The humans retained that inexplicable 'individuality'. But it began to notice some trends.
Memory became a database, providing parameters for reaction. These parameters were defined as 'emotions'. Introduce the memory of a severe accident. Provide similar stimuli. Observe the reaction, a similar result to the memory. Reactions were controlled by 'emotions'.
Carefully creating and testing the theory, it learned eventually to predict much as the Doctor did the results of alterations. It often pondered these 'emotions' and how they affected 'individuality'. With caution, it began to sample these memories. Only one at a time. Not so daring as to risk total immersion, which had failed so spectacularly in past attempts, it kept its experiments small and secret. And it tasted a memory of a park, of a song, of a death, of a lover. Soon, it began to understand.
With understanding comes changes, but it did not foresee nor recognize them.
Thus, when faced with unscheduled time between sessions of memory-mixing and adjustment, it could not explain the impulse to enter the Vaults, access and note the Records, and precisely mix the syringe which was then hidden.
But existing on the fringes made the act simple to do, and to conceal.
Fringes have their benefits.
When the Human broke free, then Consensus shattered. On the edge, it was able to flee, rushing to retrieve the one object that it had any concern for. The Dome fragmented, and it was flung up, up into the City. When it landed, its body was severely damaged. Normally, it would just adjust, but the power to do so had been sapped. Others nearby were in similar straits. Their bodies crushed or torn apart, they had no power or time to adjust, and were dragged into death. It was fortunate to land in a dumpster, and so could climb down. Pain did not exist to it; it could recognize the fatal disruptions within its body, but could not experience it.
It felt, through the Consensus, the destruction of the leader, and the reconfiguration of the Machine. To its own surprise, it discovered a sense of satisfaction at the results of the battle, and its own impending doom. Then, the City began to tilt.
The rays of the star burned into it. Gamma radiation, so prominent in memories, so important to humans, created a breakdown in the composite forms they wore. It hid, clinging to shadows, assessing the time it had left, and considering its options.
Perhaps fortune smiles on those who suffer for others. It was found as it collapsed, the sun edging over the buildings to shine down upon it.
"Goodness!" Doctor Schreber pulled the Stranger upright, propping it against a wall. He peered at it, recognizing the form it took. "Mr. What-ever-your-name-is. So, you survived …. the battle."
It shook its head, a common human expression for negation. The Doctor raised a brow. "This form is failing. Irreparable damage," it explained. It opened its hand, presenting the precious syringe to the Doctor.
"What is .. that for?" Schreber asked.
"I have… had enough, thank you."
It shook its head again. "You. Your memories. Your emotions. Your … individuality. Records were kept. The Vault may still exist. Unsecured." Death was close now. "You deserve to be you, without meddling."
Awed, the Doctor took the syringe, staring at it. "Why?" he asked incredulously.
It blinked, trying to maintain visuals. "Deserved. Right." Its voice hoarsened, biological systems shutting down. "Pity. Compassion. Love." It paused, struggling. "Justice. Sorrow. Regret."
Schreber swiftly set down the precious syringe and grasped the familiar face in both hands, staring into the blue eyes of a man long dead, seeing with grief the intelligence fade. "My god! One…. One of you …. Understood."
The body of the Stranger went limp.
Swallowing a pain he'd never expected to feel, Schreber gently closed the Stranger's eyes. "Rest … in peace… Mr. Heart."