Finally Katarin relented, half-dazed by the news she had just heard, and took a step closer to the carpet, and the men who had flown down on it.
Arcturus didn't notice her. He saw the stranger reach for his muggle gun, he saw the movement of Rawdon's hand, and then he cried out 'Avada Kedavra!' with no concern for who was there to witness it, and with one decisive wand movement, a flash of green light sped towards the man endangering Katarin. You had to mean it, but Arcturus did. The life of a muggle who might kill someone he liked, even someone like Katarin Tavehi, whom he hadn't really known since he was a boy, really wasn't worth very much at all.
He heard a terrifically loud gunshot, and then – O'Hara! What was that bloody fool doing, diving in like that? He pushed the stranger, and so Arcturus' spell went wide, harmlessly. Why hadn't O'Hara listened? Katarin was still at risk. Arcturus raised his wand again, intending to make another attempt at the spell.
Looking back as she heard the sound, Katarin saw Miguel fall, but before there was time even for her to decide what to do now, she felt a sudden, sharp pain in her arm, just below the shoulder. She clutched at it momentarily, and then her eyes went wide as she looked down at a hand covered in blood.
'Oh,' she said, quietly, and then the world swam around her, and she fell, colliding directly with Arcturus. He caught hold of her, breaking the fall, but the two of them still ended up sprawled on the carpet. A scarlet stain spread rapidly across the young woman's white woollen jumper.