While Fabian was putting out the fire, Alecto put up a shield charm that she hoped would cover both herself and her brother. Unfortunately, it didn't quite protect her enough, and she was hit on her left side by Fabians curse. She screamed as boils began erupting over her left arm that had been hit. Bastard.
In her anger and pain, she set a gouging hex at Fabian, the same one that Bellatrix had hit her with during their training session. She was too concerned with both revenge and the ever increasing boils to notice the sudden popping sounds happening around them.