Final answer:
In the Harry Potter series, Sirius Black didn't harm Ron's legs. He attacked Ron's pet rat Scabbers, who turned out to be the Animagus Peter Pettigrew, a significant character in the series.
Step-by-step explanation:
It appears there's a typo in your question, but I believe you are asking about an event in the Harry Potter series, specifically regarding Ron Weasley and Sirius Black. Sirius Black didn't harm any of Ron's legs, but there is a significant occurrence in the third book, 'Harry Potter and the Prisoner of Azkaban', where Sirius Black, mistakenly attacks Ron's pet rat, Scabbers, who is actually the Animagus, Peter Pettigrew. It's a pivotal moment in the series which reveals Sirius Black's innocence and Pettigrew's culpability in the betrayal of Harry's parents.
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