Who Don John is
Don John is the half brother of Don Pedro, the prince of Aragon who visits Messina with his soldiers. Lately beaten in the war, he is sour and resentful rather than ready to share the others' happiness. He openly calls himself a villain and prefers being hated to flattering anyone.
What Don John wants
Don John cannot stand to see Claudio happy, especially because Claudio enjoys the prince's favour. When his follower Borachio proposes a scheme against Hero, Don John agrees and promises to pay well. The aim is to make Claudio believe that Hero is not what she seems.
Don John and the others in the story
Don John approaches Don Pedro and Claudio with a claim that they have been deceived about Hero. He offers proof, and both men accept his invitation to watch for themselves. While other characters use deception to encourage love, Don John uses it to threaten a couple's trust.
Questions
Who is Don John in Much Ado About Nothing?
Don John is Don Pedro's resentful half brother and a villain who plots against Claudio and Hero.
Why does Don John dislike Claudio?
He resents Claudio's happiness and the favour Claudio receives from Don Pedro.
How does Borachio help Don John?
Borachio devises a deception intended to damage Claudio's belief in Hero, and Don John agrees to support it.