Comment on Befriending by riockman

SOMEBODY has been taking lessons from Nanoha and her lot.  Still this makes me wonder, are there circumstances in real life where two people with opposing wills who clash with their fists and weapons end up actually befriending one another by the end of it all?  I know it happens a lot in sports, but what about in a case where they could actually end up killing each other?  Do you think this defeat means friendship trope actually works sometimes in reality?