They really got to know you in all the interviews, the really try to ensure you will mesh with their team well. By the third interview it was more technical, going through previous experience, discussing the position and what you can bring to it.
I would try and show personality, i think the worst thing you can do is be fake and placate them, you will probably not end up meshing with the team well which just hurts you in the end. Also ask questions, remember you are interviewing them as well to ensure it the right fit. If you are interviewing in Vancouver, they are very active, discuss sports and fitness activities you participate in.