"Expelliarmus!" Snape cried, a sneer in his voice, "Ah, vengeance is sweet. How I hoped I'd be the one to catch you." He cast a snide look at Remus. "I told Dumbledore you were helping an old friend enter the castle and now here's the proof."
"Brilliant, Snape," Sirius replied, "once again you've put your keen and penetrating mind to the task and as usual come to the wrong conclusion. Now if you'll excuse us, Remus and I have some unfinished business to attend to." He tried to shoo the dark haired man away as he spoke. But Snape didn't budge.
Instead, he raised his wand at Sirius. "Give me a reason, I beg you...."