From the notes of John H. Watson
Eavesdropping
I was right in the middle of an odd dream. Mycroft was in the war with me, eating all my rations while I was off tending to the sick. When a young girl I had met in Afghanistan came to my tent one night to replenish them for me, out of the kindness of her heart, Mycroft had burst in and pulled her away, angrily yelling that he had warned us before about being alone together.
It was then that I awoke to raised voices. Shaking my head clear of the unsettling dream, I slid my slippers on and padded to the door, cracking it open to hear better what was happening. The voices were Lillian's and Holmes but they were speaking French. The tone was harsh and I could tell that they were arguing. I knew I should close the door and go back to bed, leaving the siblings to work out whatever strife was between them in privacy. But I was curious. Holmes would be appalled to know I was eavesdropping, but I was curious. I will try to translate what I heard the best I know how, though my grasp of the French language is tenuous at best.
"Parce que…it is none of your concern!" That was Holmes strong voice, rough and strangely emotional in a foreign tongue.
"It is!" Even upset, Lillian's sweet voice was never shrill. She was choked with emotion, so much so that I resisted the urge to go and comfort her. It would not have been appreciated by my friend.
"Pourquoi?"
"Parce que je t'aime. Tu m'aimes aussi, n'est-ce pas?" I understood that. Because I love you. Do you not love me also?
A deathly silence followed for a few moments after, until Holmes spoke again, his voice laced with a sneering anger. "Garde ton amour pour ton fiancé." Save your love for your fiancé.
She began to sob in earnest but I heard no footsteps indicating that Holmes had gone to her. "Why have you changed so quickly?"
"Speaking will not alleviate the pain."
"Ce qu'aidera?" What will help?
"Rien. So why think of it?"
Her voice lowered as she answered, adopting a resigned melancholy. "Do they help you forget?
He didn't answer, though I heard him shuffling around, probably looking for a light. He smoked in stressful situations.
I heard the rustle of her petticoat moving farther away. She was leaving. Holmes voice was low as he spoke again, so much so that I had to strain to hear him, as much as it ashamed me to admit.
"I took laudanum in University because I had trouble sleeping." He spoke in English. "I moved on from there. As to why….I do not wish to speak of that. S'il vous plait, Lily. S'il vous plait."
The door opened and closed and she was gone without answering. I closed my own door silently, praying that Holmes didn't hear it and know I had been listening to their private conversation.