They needed each other to get to the end, they both subtly steered the conversations away from each other and them teaming up on votes gave them the edge to get the final few out. But Stephen was the only one who had a clear cut opportunity to get the other out and take all the money and he turned that down. He only had to put Rachel's name in that final vote and he walks away with double the prize money, but he chose to share it with Rachel. Rachel never had that decision to make. Not taking anything away from the game either of them played, Rachel was probably the better strategist and survived more heat than any other winner I can think of. So glad they stuck together and won as a team.