Tsukasa has fought so much all his life to be the leader of the knights. There is a lot of judgement towards omegas and many believe that they wouldn't be suited for such an important position. Tsukasa doesn't care; he wears his cape and the golden rose with honor, knowing that he is deserving of such a significant role. Rui never thought less of Tsukasa for being an omega, he thinks Tsukasa is quite the interesting guy. They are both powerful so it's obvious they would form some kind of rivalry, fighting with all their strength, they probably say something like “I'm the only one who can defeat you” or “You are the only one making me go all out” a little too often for Akito not to get uncomfortable with the growing homoerotic tension.

It makes it only funnier when Tsukasa doesn't show up to the knight's daily training because his heat came earlier and Akito finds his senpai, head of the knights, curled and naked on his nest while hugging the sorcerer's cape.