What do you think makes for a really good theological conversation?
Not being afraid of being in disagreement with one another, so you learn from suddenly discovering that your friend thinks things that never occurred to you and you are not sure what to do with them! I think also working within recognisable reading regimes, so that you both are trying to negotiate how to read this book in relationship to that book. Reading together, I think, and being ready to learn from one another, is really important.
I think also that you need work to do together - for example, to write something together. Sometimes it can be quite difficult and painful, but it can also be extreme-ly illuminating. If you consider together the challenges before the church today and you have a similar sense of what they are but maybe not of how to respond to them, that can be very fruitful.