Any long-standing rivalry, whether between political parties to sports teams, will often be compared by those who adhere to neither side to the feud between a Zweilous' two heads: "You may fight all the time, but whoever wins, it all ends up in the same stomach." Yet this is saying betrays a lack of comprehension ofthisconflict, for while a Zweilous' heads compete both in gluttony, this is merely a proxy for a greater battle for control over their shared body.
Although Zweilous frequently gripe at one another, these pokemon are rarely paralyzed by indecision like the Dodrio, and rarely if ever resort to fratricide. Some early researchers claimed this is because the Zweilous take turns, but their turns are never even, for these researchers had a superficial understanding of a far more intricate competition.
During each Zweilous head's turn of leadership, it puts its ability to the test to gather as much food as possible; in captivity, where food is alwysplentiful, battles won are used instead. The other head criticizes as often as it likes, but does not attempt to actively rebel, and whenever food is found the leading Zweilous head maneuvers into a position where it can far more easily eat – although with these pokemon's long necks, the difference is not all thatextreme. After a set period of time, determined by how large a food advantage the larger head has gathered (for these pokemon keep score) the two Zweilous heads switch control, and the hungrier head must attempt to make up the difference.
Although the rules of the game require each head to gain control for a significant amount of time, Zweilous do keep an overall tally, for with evolution the losing head is subsumed, and the victor becomes the unchallenged brain of the Hydreigon.