Alarmed by the shout, Sirius lowered himself closer to the ground, grey eyes trained on the young wizard and, more specifically, his wand. Though there was something undeniably familiar about the face of the other man, Sirius's mind was warped by fear and he couldn't quite piece together enough of a memory to recall who the wizard reminded him of. Sirius continued to slowly retreat, only pausing at the plea.
Seeing the wand being holstered, no longer the imminent threat it had been only moments before, Sirius felt as if the vice around his ribs had finally loosened, and he was once more able to breathe. Still, he remained on edge, eyeing the wizard and getting no closer, his mind racing as he tried to place his features. All of Sirius's memories were touched by the Dementors, violated and shredded, leaving his recollections vague and unhelpful. With each passing day, he began to feel more normal but anything close to how he had been was a ways off yet.
Longbottom.
A flood of unconnected memories flooded Sirius, a blur of images and sounds and feelings, tangled with a deeper dread that Sirius had never been able to shake. Shifting at once into a person, Sirius leaned heavily on the table. Since his escape, he'd hardly felt sturdy enough to stand at his full height and even now, his clothes didn't seem to fit him right, hanging off him where once they had been fitted.
"A friend of Harry's," Sirius echoed, studying the boy's face. He'd barely been able to learn much of his godson since his escape and had only the honour of meeting Hermione and Ron (and he still felt rather terrible for the bite). "I don't believe we've met."