As Remus tried to come up with a plan to capture Peter without endangering any students, as a professor, and without risking Peter fleeing, Sirius continued to lurk in the Forbidden Forest.
He would explore the woods, occasionally getting in dangerous situations. Running into centaurs, giant tarantulas, and whatever the Forbidden Forest has to offer. He would also sit at the outskirts and watch the professors, the students, and other residents of Hogwarts go about their days, outside the castle. Occasionally he would see Harry or Remus. Remus made it very clear that he is under no circumstance to approach Harry.
Sirius was growing impatient, however. It's been a couple of months and it seems like they keep going down dead-end roads and hitting walls. He was getting tired of waiting.
It was a warm-ish May evening when he recognized the kid from the Daily Prophet article. The Weasley boy. Should he go for it? It won't be long before Peter gets wind of what he and Remus are after and make a run for it, but Remus would definitely not approve of it…
During that moment of hesitation, Weasley was joined by two of his Gryffindor friends. It is riskier to make a move now, but the idea was already in Sirius's head, and it seemed very tempting. Just grab the rat. No more devising clever plans. They've tried Remus's way, it's time to try his way.
Sirius made a run for it. He ran towards Weasley, and grabbed by his ankle. Weasley screamed.
"Get him off me! Get him off me!" He screamed as he was getting dragged on the grass.
The dark skinned boy grabbed Weasley's hand and tried to stop him from getting dragged away, but he just ended up falling forward and letting go when he did. The other kid just stared, terrified, at the huge black dog.
Sirius made his way to the Whomping Willow and into the tunnel to the Shrieking Shack.