"Robin won't stop talking about you, have you thought about my proposal yet?" Batman asks you, joining you as you watch the city from the roof of a building.

Bruce had been trying to get you to join the "batifamily" for a while, sending Dick to patrol with you wasn't part of the plan, but it was the last confirmation he needed to have you on his team. Robin raved about you to Bruce and Alfred, from the way you fought to the plan you made. So Bruce was willing to offer anything to have you join the team.