Why do iago and roderigo go to brabantio's house to tell him about othello and desdemona's elopement? othello?

Iago is both racist, backhanded and takes the classic 'evil' but intelligent character, by going with Roderigo (who loves Desdemona) to her fathers house he will gain favour with Roderigo who he calls a 'fool' so he can manipulatrac him later get one up on Othello who he hates.