"Benedict, I don't think the flashlight caused him to kill a man!" John hissed at Sherlock, almost forgetting that they were using fake names. Sherlock wrote on the whiteboard, "If he was as dangerous as everyone says he is. Why didn't you get attacked?"
John pondered, "He did lead me to critical evidence."
"Exactly..!" Sherlock pointed behind him. He wrote out theories after theories. He only stopped when he came across one that he'd never consider on normal basis. "The Doctor said that this thing was a machine, didn't he?"
"Yes, he did," Clara nodded. Sherlock pointed, "What are machines and robots prone to do?"
Clara pondered. John tried to think of an answer. He stopped and looked to Sherlock, "They're prone to having bugs."
"Precisely," Sherlock nodded. "He's a machine. Which means he has his own bugs, one of them involves bright lights."
"That would account for the attack," Moya blinked. Clara nodded, "What if the bug mistakes bright light as an act of aggression?"
"You're saying light causes him to go berserk?" John looked at Sherlock. Sherlock grabbed for the marker and began to write on the whiteboard. "Remember those animatronics from the pizzeria. They had to ban cameras from using flash because it messes up the animatronics?" Sherlock glanced behind him. John nodded. He stopped, "They said that it resets the animatronics."
"Right," Sherlock continued to write on the whiteboard. John shook his head, "He didn't go berserk when the flames from the homeless' barrel rose up and lit up his eyes."
"It has to be bright, brighter than fire. Brighter than streetlight, brighter than the moon!" Sherlock said fervently. John blinked, "The flashlight the patrolman used was pretty bright."
"Yes, exactly… Martin," Sherlock nodded. "I believe old flashlights don't affect him, but newer flashlights…"
"Would cause problems because they're brighter than the old ones. And some of those new ones you can concentrate the light," John finished. Sherlock sat the marker down, "I believe we have our cause. The patrolman flashes light into the Plague Doctor's eyes. The flashlight is brighter than older models so it's strong enough to cause the attack."
"But, why did he attack the patrolman?" Moya asked him. Clara then answered instead, "Because of the programming."
"Precisely, Clara," Sherlock nods. "His programming must be so full of bugs he must be crawling with them! Whoever programmed him did a shoddy job of it."
"But, then who made a robot and dressed him like a damn plague doctor?" John blinked. Sherlock shrugged, "I don't know."
"That's why the Doctor wants to crack his programming," Clara told them.
Sherlock looked at Clara, "How would he go about it?"
"I don't know, Benedict, it's the Doctor we're talking about," Clara sighed. They soon left for the labs to see how the Doctor was doing on his end. Sherlock and John falling back as Clara and Moya walked ahead. John shook his head, "Bloody hell, this reminds me of a Christmas special!"
"Stay sharp, John. There's still more things that meets the eye," Sherlock eyed him. John sighed, "I can't believe it though, and who would program a robot to go universe hopping?"
"Who's to know, John," Sherlock held his hands behind his back as he walked, pondering to himself. John rubbed his eyes, "Is it too much to pray this is a dream?"
"Yes," Sherlock marched on. John watched him catch up with Clara and Moya, John shook his head as he followed Sherlock close behind.