The assassin laying on the floor groaned as his burnt body was giving out, succumbing to death. Yari appeared out of thin air, pearl tears streaking down her face, as she let out a gentle cry. She raised her faintly glowing blue dagger high in the air. His eyes met hers as(more) he muttered a gentle word, his voice laden with death's rattle.
Squeezing her eyes shut, she choked back a sob as she buried her blade deep between his ribs. This was the cycle of life. Yari understood that but it didn't stop her from sliding down to the floor, crying gently, as she cupped the charred face of her fallen brothren. She knew that if it wasn't him, it would be her corpse, This is the way it had to be, but that didn't stop her from slumping to the floor both in sadness and relief. The only other person she knew as family was dead on the floor in front of her, and she was surrounded by strangers who didn't trust her. Yari wiped her face with the back of her arm, understanding that now she was truly free and truly alone. And she was terrified. The cult would hunt her to the ends of the earth but no one could capture her the way her brother could have.
They weren't ordinary drow. This becomes clear to Ignis as he studies her. Upon inspection, he realizes Yari helped him kill the other drow in combat. Her knives are in multiple bodies in the scene, pinpointed in vital spots of the casters.
The strange part about this is that no one saw her during the entire combat. (For my new players, thats a big deal because when someone is stealthed, they are automatically popped out when they attack)