When signing up to fight another human being, a certain amount of animosity towards said individual is to be expected.
It isn’t always a given, Dustin Poirier and Khabib Nurmagomedov can attest to taking part in a respectable contest at UFC 242. Nurmagomedov even going as far as to wear his adversary's shirt after the bout and auctioning off the clothing, with all proceedings going to Poirier's charity, The Good Fight Foundation.
That match very much falls into the category of one off, as battles in the octagon (the hotly anticipated ones) tend to involve heated exchanges both inside and outside the cage.
When a verbal rivalry gets physical, that's when the fans truly begin to engage.
Press conferences tend to house their fair share of physical skirmishes, yet that doesn't make those incidents exclusive. Fighters are a wild bunch and, if provoked, will strike in a parking lot, immediately after a sanctioned fight or even on a reality TV show.
All's fair in love and war and these warriors aren't prepared to wait until they're in the octagon to prove it.