Ouroboros is the tail-eating snake of legend; which when used as a symbol it usually represents cyclicality. It should be the symbol for Open RvR in Warhammer Online, especially in regards to Keeps. In Warhammer Online, I think the developers really wanted the two snakes (Order and Destruction) to fight head on, but I think the players looked at the eternal snake and decided that “the tail tastes better.”
The tail in this case is an undefended Keep in another racial pairing. There are six Keeps in Tier 2 and 3, two in each racial pairing (I have not yet been to T4 to experience Open RvR, and so refrain from commenting as of yet). I have yet to see more than two massive zergs, one Order and one Destruction, in a Tier doing open RvR. So two snakes have their pick of Keeps to devour. A warband could wait around and defend a Keep when they think an enemy group is coming, but humans (especially MMO players) want to go the path of least resistance. In this case, that would be an undefended Keep in a sleepy RvR lake.
The other night a two-warband Destruction group decided to sack Keeps in T3. There were very few defenders at any of them. An Order group formed up to attack a Keep we had just finished sacking, moving on to greater glory thereafter. We went back, successfully defended the Keep, and then a small bit of drama formed. People didn’t want to stay and defend the Keep anymore. “Why defend, let Order have it, and we can just take it back. Rewards (renown and loot bags) seem better that way.” We sacked four Keeps that night before I crashed. At the very end, we came upon the Order group that was in the process of sacking one of Destruction’s undefended Keeps in another racial pairing with 1-2 warbands. We didn’t seek them out. It was more that our snake ate the tail of the other snake faster.
Tobold recently discussed “moving the cheese” in MMOs to get players to move around. I honestly believe that for T2 and T3 Keeps (can’t comment on how T4 runs yet) the cheese needs to be moved so that eating the other snake’s head is worth more than just eating it’s tail all night.