Mercutio has ill-will towards both of them
In my opinion, the correct answer is B. His mystery feeds their imagination. The children have never even seen Boo, so they like to imagine and envision different spooky details about him. Jem fantasizes that he catches and eats squirrels and cats, which is why his hands are always bloody; he drools, his teeth are rotten, he has a dreadful scar on his face, etc.
Answer:
He was arrested and imprisoned upon being caught marrying Christian couples and otherwise aiding Christians who were at the time being persecuted by Claudius in Rome.