Tsukasa is a Knight. Head knight actually, of the Knight's of White. Which is exactly why it was all the more wrong for him to simply be here with Rui (much worse date him), a powerful sorcerer. Law says Rui should be turned in and executed, but... Tsukasa simply couldn't bring himself to. Rui wasn't a bad person, he simply used his magic skills to conduct research on things he found interesting, he wouldn't (intentionally) hurt anyone with it. He may be a little mischievous and have done some petty crimes like stealing apples, but it was just something about Rui that made Tsukasa want to keep him from harms way in any possible way. Was it wrong? Absolutely. Tsukasa should have turned Rui in months ago- or better yet, executed him himself. But here he was, in bed with the man he was both hopelessly in love with and needed to stick on a sword.
Rui had been overworking himself on his studies again- so, Tsukasa made him go to bed. Somehow, that had him finding himself being used as the sorcerer's personal pillow, Rui snuggled up onto Tsukasa's chest as he quietly snored. It was the only way Rui could sleep good.
The Knight held the sorcerer close, gently running his hand through Rui's hair while quietly contemplating the precarious situation they'd gotten themselves into. He knew it was dangerous and that the other Knights would kill him if they knew.
He gazed down at Rui's sleeping form with a mixture of fondness and worry in his eyes, as he tried to mentally talk himself out of falling any deeper in love with the sorcerer.
"What am I going to do with you...You always make things so difficult." He whispered in a resigned sigh.