As his mother's equine-shaped Patronus galloped toward the attackers, Al's own cougar-shaped form seemed to streak across the sky as though chasing down its prey, leaping toward the Dementor it was nearest. Forcing himself to think happy thoughts - the day he received his letter to Hogwarts, being named Head Boy, the look of pride on his father's face when he graduated - the young man stepped slightly away from his mother and in front of a small group of Muggles who had gathered behind one of the vending carts.
His Patronus pounced upon a Dementor that turned their way before taking a protective stance around the group, pacing back and forth and eying the creatures it was meant to stave off. Al's entire armed seemed to throb as he kept his aim trained on the cougar, although he did risk a glance at his mother to see how she was faring. And even took a second to call out steadily, "Mum, we need to get these people out of here!"