The moment after our eyes met, Sherlock turned on his heel and walked out of the emergency room.

I didn't follow him immediately. My heart was pounding in my chest, and I had to take long, cleansing breaths before I could plaster a smile on my face and turn to John.

"John, I need to check on one of my patients," I said calmly. "But before I go, I need to make sure you're going to be all right."

Before John could even speak, Mrs. Hudson interrupted. "I'll take him home as soon as the doctor says it's all right. And I'll stay with him tonight."

"I'll see them home," Lestrade added gruffly.

John sipped at the tea from his dinner tray, setting the cup down with a bang. "I wish everyone would stop taking care of me like I'm a bloody invalid."

"They are taking care of you because they're your friends," I told him. "And because it comforts them to know they're comforting you."

John looked appropriately contrite. "I know." He reached to squeeze Mrs. Hudson's hand, and nodded to Lestrade. "And I appreciate it, I really do."

"I want to help you, too, John," I said. "So I want you to call me tomorrow and set up an appointment. Will you do that for me?"

"Yes, he will," Mrs. Hudson supplied, and John gritted his teeth, fighting the urge to protest.

"Great." I handed her one of my business cards and then turned to pat John's shoulder. "If you need anything before then, you just call me," I said. "Day or night, John. Do you promise you'll do that?"

"Yeah," he muttered. "Thank you."

Offering smiles to his companions, I walked out of the emergency room. Stepping into the corridor, my eyes were peeled for Sherlock. There were a few people in the hall, but none of them were wearing surgical scrubs and none were watching me, so I walked casually to the service lift and pushed the button.

In the basement, I walked to our flat, reaching for the keypad outside our door. At Mycroft's insistence, the door was armed from the outside as well as the inside, preventing anyone from walking through the door without triggering the hospital's alarm systems.

At that moment, however, the door was slightly ajar.

I pushed it open and startled at the scene in front of me. Mycroft Holmes stood in the middle of my office, his hand raised to strike his brother.

Everything seemed to move in slow motion then. I saw Mycroft's fist make direct contact and Sherlock's neck snap back with impact. The strike was hard enough to propel Sherlock 180 degrees before he fell to his knees with a dull thud.

I yelled but it didn't stop Mycroft from pouncing at his brother, jerking Sherlock to a standing position. Mycroft held fistfuls of his brother's scrubs, yanking him close so their faces were inches apart.

"Do you have any idea what you have done?" the older man snarled. "You stupid, stupid man. Do you not realize the expense this little ruse has cost?"

"Mycroft, STOP!" I tried to pry his hands from Sherlock, but the man was much stronger than I was. He elbowed me away and continued his attack. "Dear brother mine," he hissed in a deadly low voice. "It would have been more cost efficient if you'd actually met your death."

Sherlock just stared into his gaze, his face expressionless and pale.

Incensed, I shoved Mycroft as hard as I could, and he broke his grip on his brother's shirt. Sherlock stumbled and slumped to the carpet, his limbs sprawling. As Sherlock curled himself into a little ball, I stood over him, a human barrier between him and his brother. When Mycroft stepped toward Sherlock, I thrust out my arms to keep him away.

"Mr. Holmes, you paid me to keep your brother safe," I said. "And that's what I am doing. Now get out before we both do things we will undoubtedly regret."

Mycroft's face was flushed with exertion and anger, his eyes cold as death. For a moment, I thought he'd lunge again. Instead, he turned on his heel and marched to the door of our flat.

"I'm overriding the door codes permanently," he said, stabbing numbers into the key code. "I am not helping you any further, Sherlock. You want to wander the halls of St. Bart's, then wander. You want to put John Watson in mortal danger, then do it and spare us the expense of keeping him alive.

"And if you want to climb back onto the rooftop, and jump again… then be my guest."

And with those terrible, horrible words, Mycroft Holmes walked out of his brother's life forever.