What I saw wasn't Isabel. At least, not anymore. What was under those covers was a poor, pathetic silhouette of her, and what was left of it. Her once-sleek curls were sprawled all over the place, a mass of frizzled hair. That milky-white complexion was gone; her skin was dry, like stretched leather, full of black spots and fresh open wounds here and there. She'd become scrawny and despicable, a sorry sight to see.
And she was awake. The pain had kept her awake through the night, I could see her round, bulging eyes staring up at me. She opened her mouth and tried to speak, but no words came out. Only these half-eaten, gurgling sounds. She couldn't even move anymore, it probably hurt too much.
I sat beside her, on the edge of her bed, not afraid. Why should I be frightened of my own sister? I didn't even say anything; we just sat there, staring at each other. She just looked at me with those big, pleading eyes of hers.
I grinned.
I bent down at her, so closely until the tips of our noses were almost touching. Then, brushing away some hair from her ear, I whispered that rhyme she herself used to sing. Now I knew why she was singing it. Now I knew what it meant. Upon hearing it, her pupils contracted, and she looked up at me fearfully. She knew what it meant, too.

Ring around the rosies
Pockets full of posies
Ashes, ashes
We all fall down…

She looked at me. I smiled and pointed to the window. The sky was still tinted with orange from the cleansing bonfires outside. Then, I pointed to her.
Planting a small kiss on her forehead, I whispered, "Soon."

By the time I was closing the door to leave, Isabel was already silent. I even closed her eyes for her, like any respectful relative would do for their dead.
And as I was heading back to bed, my little friend nudged at my heel. I turned to him, but careful not to come too close. But reaching for my pocket, I placed a little gift on the floor for him. I watched him nibble on it gratefully.
Like I said, those perfumed masks were useless. The plague was no airborne epidemic.
In fact, I was staring at the feared Black Death in the face right now. And like I also said before, if you pay enough attention, you notice things no one else does. And with so many people in such a big house, nobody would ever notice one small rat.
I smiled, and watched Black Death nibble on a piece of cheese, while I hummed my little song.