yesterday i was in breifine on my stealther, observing a lvl50 animist/menta duo farming/powerleveling a druid. I was waiting for a good moment to strike, as i had seen the Animist sit down between pulls, sometimes for a longer time.
While standing there suddenly a briton popped up besides me. I instinctively moved away (since we were close to shrooms and us fighting each other would have been certain death).
Then i thought to myself, well...now or never, and engaged the animist. Without the briton i would have died without even killing the animist, i couldn't watch him fight the menta, but i didn't get stunned, and after killing the animist there was noone else in sight.
I thought to myself, that from THEIR perspective it must have looked like crossrealming too, while from my it was just me (and the briton) being opportunists.
Me and the briton met a few minutes later nearby, i wasn't sure if our unwritten truce was still in effect and before regrets happen i engaged and closely won. If you are reading this *briton* and DIDN't want to attack, i am sorry but i couldn't take my chances so deep in enemy territory
Long story short, short "cooperations" happen in DAoC all the time and are what makes the game great.
In a three-realm-fight no realm wants to be the one that gets teamed up on, so teaming up with one enemy to kill the other enemy is a valid approach, and often has nothing to do with crossrealming
PS: /titlegore