In the third room, the three men were standing outside of a cell. In the cell was a familiar figure attached to an IV drip.
"Molly," Sherlock's voice was barely a whisper.
"Eurus!" Mycroft roared.
"What did you give her?" John cried.
Sherlock walked over and put his hand up to the glass. "Molly," he echoed.
"I'm allowing the two of you to switch places, Sherlock," Eurus sang. "You know: walk a mile in the other's shoes, get a taste of your own medicine, et cetera, et cetera, et cetera."
Sherlock closed his eyes, resting his forehead against the thick glass barring him from Molly. His hand curled into a fist as he swallowed hard.
"Oh god," John ran his hands through his hair.
"Did you make a list?" Mycroft asked, almost inaudibly.
"What fun would that be?" chirped Eurus. "I can't give you all the answers. That's hardly fair."
Sherlock looked back at his sister scornfully.
"Anyway, she has about another minute before the drugs take full effect."
"We're supposed to just sit here then?" John asked.
But Molly's trip was already starting. Her bloodshot eyes darted around her enclosure. She began squinting as if the lights hurt her eyes.
Sherlock recognized everything she was experiencing. It pained him to see her forced into the choices he made. The fact that her trip was coming so quickly was definitely not a good sign.
Molly started scratching at her skin, first at her arms moving up to her neck and face. She started panicking, screaming unintelligibly.
"We have to calm her down," Sherlock said forcefully. "Molly! Molly, can you hear me?"
Molly's frantic gaze met his. She clutched the IV stand. Her breathing was becoming shallow and ragged. She charged at him with a blood-curdling, inhuman scream. She crashed into the glass beating the IV stand against Sherlock's reflection. Tears welled up in her eyes then. "Dad?" she trembled. "You look sad… NO! DAD! DON'T DIE! DAAAAAD!" She started running circles around the cell.
"Molly," Sherlock tried again to get her attention, his voice unsteady. "Molly look at me."
"I can't… I can't feel anything," Molly's voice dropped to a whisper.
"Molly look at me," Sherlock persisted. "I can see your arm. Can you see it?"
"Arm. Yes!" Molly shrieked.
"Good, look at it. Can you feel your pulse?" Sherlock pressed on despite his own agony.
"Yes," Molly said flatly. "Thump thump… thump thump..."
"Good, focus on that, Molly."
Molly began to truly imagine what an eternity would be like… where it is forever. There is no end to look forward to. There is only the current state of hopelessness, there is nothing positive, nothing good. Molly felt simply condemned. SWIM began to whisper "I'm sorry" over and over again. She slid down the glass wall, crumpling on the floor. She banged her head against the wall, quickly gaining force and speed.
"Molly, stop. You're going to hurt yourself. Please," Sherlock begged her. "Please."
"I'm sorry," she wailed, seeming not to have heard Sherlock. Her eyes rolled back into her head as she passed out on the floor.
"Molly! Molly can you hear me? Molly wake up! Molly! Please!" Sherlock looked back to his friend. "John, please, you have to help her!"
"Mate there's nothing I can do from out here," he sighed.
The next door slid open.
"We can't just leave her here! She could die!" Sherlock was growing increasingly desperate. "John! I can't just leave her here!" He looked back at Molly's small frame lying helpless on the stone floor. "MOLLY! WAKE UP!"
"Interesting," Eurus mused. "You're willing to risk your own life with drugs, but watching someone else, someone so ordinary and insignificant, do the same…" she trailed off wistfully.
"Stop it!" Sherlock raged. "I choose to use. Occasionally. Molly didn't choose this! You forced her!
"So?" Eurus smirked. "Calculated risk, just the same."
"SHE'S NOT WORTH THAT RISK!"
"Why not? Surely someone else can supply body parts for your experiments."
"It's not that… I- I… I love her." Sherlock dropped to his knees beside Molly's unconscious form. "I love her. And now I may have lost her."