Okay, so our protagonist is minding his/her own business, usually walking around the town of his/her birth and/or recalling memories of a fonder time. Then, he/she sees the Worthy Opponent / The Rival / the Anti-Hero /etc. doing the same. Naturally, upon seeing each other, they decide to duke it out, more for the sake of recalling old times or bonding than actual fighting over good and evil. After exhausting themselves (because they're so evenly matched that neither can defeat the other), the two rest on the ground and just talk and bond, temporarily forgetting that they're supposed to be enemies or on different sides.