Oh believe me the challenging eachother part is something I know quite a lot about. My brother and his friend have a CONSTANT battle to see who is truly superior, though they are quite equal. My friend and I do not do that, we see very clearly that either of us is better at different things and when it is time and that person is better at such thing we step aside to let them lead. =)
My brother and I have a battle of wits constantly, we turned a nice, calm canoeing trip with our youth group into a crazy and determined battle of strength and wits to see who could get there not only first but without getting the canoe tipped... he won because his partner threw a water bottle into the river and my partner insisted we turn around and pick it up.