Gil Grissom was someone who many never really knew well. He was known as the bug guy, simply because of his collection of insects. In truth he hid many things from people. He hid his past and everything and everyone in it. So much so, that no one could ever get anything from him. Grissom hid it very well for many reasons. One of the reasons was simply because he knew now that he wasn't looking any innocent than Walker was. In truth, he himself wasn't saintly. He knew the beetles, the ones that squirmed in the container on his desk. It wasn't all smoke and mirror as he made it. The beetles did come from the Plague Doctor, but they didn't come from him originally, they came from him. Grissom had worked for the Corporation at a time, as a biologist. He was studying beetles, seeing if they could be modified to be used for other things that Sofia wanted. His work never worked out, as the beetles kept escaping their enclosures and eating the leftover foods left in the break room. Yet one day, he noticed the beetles were attracting the attention of the ravens for some reason. The ravens kept trying to eat them and the beetles weren't in a hurry in escaping the ravens' clutches.

Grissom studied the aftermath and found that the beetles were mutated, no longer the simple North American carrion beetles he had, and they were far different from their former. He tried to trace the mutations back, but could never find the source. Sofia didn't care; she prized her Subjects more than beetles and ravens. Grissom kept an eye on the beetles and found they always came around after the Subjects were allowed to roam the halls. He eventually found out that the beetles colonized within the Subjects, consuming their weight in tainted flesh and becoming mutated.

Telling Sofia was something he couldn't do. She was never keen on insects as he was and she would've never allowed the beetles to continue existing. So Grissom kept quiet and went about his work. He stayed with the Corporation for sixteen years before he eventually transitioned out and found new work, eventually winding up at UNIT. He managed to get out of explaining his entire career history because the Corporation had modified phone numbers and the like to fool those who ever tried to look into the Corporation. Grissom heard of Alice Walker, the former Warden-Commander, taking up as a Patrolman for the London Police Department, which UNIT had contacts with. They knew better to associate with one another or even give any sort of suggestion that they knew each other prior.

Alice was the same as before, with less arrogance since he was demoted from being the Warden-Commander of the Keepers to being a simple Patrolman. He transitioned out of Corporation purely because he feared for his life as the Subjects were becoming increasingly irresponsive to the Keepers and their control rods. He feared for his life and that was a fact that he kept until his death. Neither Grissom nor Walker knew what happened to the Corporation after they left for this universe. They rather not, as Sofia had threatened anyone who let it slip what was really going on in the Corporation would be forced into the Conversion Process by brute force.

They knew what became of those who were taken into the Conversion Process, some died, some didn't but died later, and so forth. Walker himself was responsible for taking the most people to be converted, when he was a Guard and had to go out and bring back subjects for use. Walker never really recovered from the fact he condemned many to death or a cruel form of imprisonment, in fact he worried that the Subjects would avenge their fallen brethren by killing him and the other Guards involved. Walker wasn't all there to begin with, a common thing amongst the Guards who worked in the Corporation . They never did wrangle with that particular conundrum.

Whatever the case might've been, they were both out of the Corporation. All was well until Walker was killed. Grissom at first never thought about it, as he wasn't inherently responsible for the Subjects conversion. After seeing his beetles happily colonizing inside Subject Delta and their abilities to mutate ravens into becoming his eyes and ears, though, Grissom feared that Delta would come for him next. What was more was that the Subject was out in the first place. It either meant it escaped or the Corporation Grissom tried so hard to hide wasn't able to handle the Subjects much longer after he and Walker had left. Grissom wondered what became of the other Subjects and if they had escaped as well. There were only five when he left but by that time Sofia wanted to start on the next series, so he didn't know if any more were successfully converted.

Sofia wanted to stop the Cybermen at any cost—or any threat for that matter and decided using humans was good enough. She wanted to see if she could use the Cybermen's philosophies of deleting undesired traits and weaknesses in her own fashion. Suffice to say she succeeded and she decided that she wanted to be held to the highest regard—and decided that having her own personal army would be a start. She never cared who the subjects were when they were brought to be converted—they were all numbers for her. The only thing she ever treated remotely human was her daughter—Emma. Though, she kept Emma far away as possible from the research.

Grissom didn't have a dog in those fights. He was a researcher, nothing more. He studied insects and decided their usefulness; he wasn't a part of what happened to the subjects. In the end, Grissom figured that Subject Delta wouldn't come after him. After all, he overheard some conversations of passing soldiers leaving to escort the Doctor and his companions, all saying that the higher ups wanted Subject Delta dead. Grissom's fear about retribution was null and void, Subject Delta would be dead by the time the Doctor heard enough about the Corporation from it before the soldiers would kill it.

Grissom sat at his desk, he was reading through the paperwork as he went about signing the ones that required his signature. He glanced at the beetles that moved around, he was waiting to hear back from higher up to decide what would become of the beetles. Grissom expected the beetles to be destroyed given their tainted nature, yet he wanted to keep them as a sort of memento. It was something he was known for doing when it came to insects—even those he held prior to being a part of UNIT. Even if they perished anyway, he'd at least keep their carcasses on display as he had done for the others he collected during his years of service under UNIT. As for the raven, since it was not affected, it was to be given to a bird sanctuary in Cheshire and for now it took up residence in Grissom's office until the paperwork was accepted.

Grissom shuffled the papers and went through them one more time, taking quick swigs of his coffee and bites out of his hamburger. The papers would plenty and Grissom knew for a fact that he'd had to sign them all within the night or else he'd hear about it from his superiors the next morning. The raven was calmly pecking at the food provided, the only sounds coming from it were its beak smacking against the seeds and pellets. Just as Grissom was finishing up, Nick stuck his head in through the doorway and told him that the lab needed him to sign off on a few things. Grissom nodded and stood up, wiping down his clothes, crumbs scattering on the floor, and walked with Nick toward the lab, the technicians needed his signature for some equipment to be brought in. Grissom obliged and signed off on the request, he was then asked about the beetles by the technicians who were curious about them.

"Don't you think it's a bit dangerous to keep them around you?" Sara asked him. Walter nodded, "I think you ought to destroy them right then and there."

"What are you talking about, they're still beetles," Grissom shook his head. The technicians shirked in their spots and bit down on their lips. Nick sighed, "Look, there's a reason why Grissom's a bug expert. If he says they're fine, then they're fine."

"Thank you, Nick," Grissom nodded.

Grissom returned to his office, closing the door behind him, he took off his glasses and rubbed his light blue eyes. It was going to be a long night, he knew it. What with the Doctor chasing around the Plague Doctor and whatnot, Grissom was going to be asked under the sun about the beetles and the ravens. He stopped when he saw the container on the ground facedown. He went to it and propped it up; the beetles were wiggling their legs as they tried to regain their footing. Grissom helped them as he sat the container down on his desk. He was bemused on how the container would've fallen off his desk, he kept it away from the sides as he always done and it was too heavy to be accidentally moved on its own. Grissom concluded that someone must've been in his office and knocked it off accidentally and cowardly ran off, afraid of what he might've said if he found the culprit in his midst. As Grissom sat down, he looked at the beetles as he sipped on his coffee. They regained their footing and huddled closed to one another as Grissom watched them. He sat down his empty coffee mug on the table and cough lightly, he drank the coffee too quick. Grissom held a fist on his chest as he coughed, the pain subsided and he sighed. "I have to stop doing that," Grissom shook his head. He stopped when he noticed something off. He counted the beetles in the container; he stopped when he got to six. There were two beetles missing, one medium sized and one very big one. Grissom looked under his feet, under his desk, near his filing cabinets, but couldn't find either one of the beetles. He glanced at the raven whose head was down, it was shaking violently, and it subsided when the raven raised its head up, revealing amber eyes.

Grissom stumbled backward and pointed, "Impossible!"

An idea struck him and he went back to his coffee mug and looked inside, there was a thin black but noticeable leg of one of the beetles at the center. Grissom touched his throat. "I-I couldn't have…" he trailed. He felt his world around him spinning, he couldn't feel his skin, his face was cold, and he glanced at window to his office and saw a terrifying sight. He saw the Plague Doctor standing there, where he was. Grissom fell to his knees as he clutched his head, sharp pains intensified in his brain. Thoughts that weren't his started to attack his own, he heard a foreign voice that boomed, it sounded metallic and indiscernible. His memories were being wiped away and replaced, no longer did he remember graduating at the top of his class, instead he remembered a village that he was born and raised in. He remembered Alice Walker as a family friend who was a bit weird, but nevertheless a good man, until one faithful night where he abducted him, smacked a baton over his head and dragged him into a van. He remembered the horrible things done to his body; the awful tastes of the medicine they force fed him, how he felt his life was slipping away and then some. How he woke up as a hulking monstrosity meant to kill Cybermen without so much as blinking, not that it'd matter much since they cut his eyelids off and then some. Grissom's own memories were wiped clean and replaced with someone else's and there was nothing he could do about it. Grissom couldn't scream as he slumped near his desk, his eyes closing on their own and his mouth remained gap.

It felt like hours if not years since it passed. Grissom's eyes slowly opened and he glanced around his office. He glanced at the raven that looked down to him. Grissom stood up and ran a hand through his hair as he looked at the reflective sheen of the diploma that hung near the filing cabinets. His head turned to the raven as it chirped, he went toward it and rubbed it on the top of its head. The raven lovingly head butted his finger and Grissom smiled. He then checked the time, it was close to five, and the Doctor and his companions would be coming back to UNIT shortly. Grissom readied and went about the room pouring onto the floor the various liquid that he kept on the shelves. He poured much of it on the desk, coating the container containing the now dead beetles, he would continue this until he finished. Grissom tilted his head toward the left; there had been an accident in the lab, the amber substance caught fire and has begun to overtake the lab in mere seconds. He smiled. Suddenly smoke alarms were set off and a woman blared over the speakers imploring everyone to vacate their workstations and to head toward the safety zone. As smoke bellowed from the lab, trekking through the halls, Grissom picked up the birdcage and calmly walked into the smoke. He stopped and turned to the office and rummaged through his pockets, pulling out a matchbook and a packet of cigarettes. With them lit, he tossed them onto the wooden desk as he left through an unguarded exit door, his raven cawing in the distant as they seemingly disappeared into the night.