Nakuru Akizuki. The non-binary thorn in the side of Touya and Yukito's blooming relationship.
They make their appearance at the very beginning of the Sakura cards arc, as the new transfer student in Touya and Yuki's class. Like many girls (or female-presenting persons) before them, and most likely many after them, Nakuru seems to develp a thing for Touya. Perhaps develops isn't the right word. It's more like it generates spontaneously out of nothing. Nakuru is very insistent... probably much more so than anyone Touya has ever had to deal with before. They are not shy, and they are very... um... affectionate (that's one way to put it, anyway), and no amount of glaring and protests on Touya's side is really enough to intimidate them.
The very first time we see them is simply typically Nakuru. Sakura and her friends run into Touya and Yuki after school. Touya is hiding from the new student in the class, and Sakura wonders why. Then out of the blue, Nakuru glomps Touya. I'd say glomping their "delicious feast" (that's what Nakuru calls him) is probably one of Nakuru's all-time favorite activities.
Speaking as a rabid Touya/Yuki fangirl, I'd like to point out that I don't have a problem with the glomping in and of itself. If they're kind of excessive... well, it's understandable. It's Touya we're talking about, after all. It's the smug, narrow-eyed way they always look at Yuki while feeling up poor Touya, the way they tell him not to get in the way that makes every one of my brain cells scream something along the likes of YOU BITCH!!!!
Because what that sly look makes perfectly clear is that they're aware that there's more to Touya and Yuki's relationship than meets the eye. Nakuru is not like Youko, who only guesses that there's someone Touya likes after he turns her down. Nakuru knows... and just doesn't care. They tries their very best to come between the two of them. They seem to have a sixth sense for knowing just when to show up in order to interrupt an intimate moment between them... in fact they pop up out of nowhere practically every time that Touya is trying to tell Yuki that he likes him or that he knows about him. And they takes every oportunity to get get Yuki alone and tell him to stop interfering between them and Touya. And Yuki, in typically Yuki fashion, does not tell Nakuru to go to hell. At first Yuki seems oblivious to the way they act around Touya, or at least, he doesn't seem to mind. One could say, I suppose, that he's not threatened by them... except I don't buy that. There's one scene in particular, on the morning that Touya gets to school to find Yuki asleep at his desk, where it's very clear that Nakuru's actions do affect Yukito. You could say he's just really tired, I suppose, but I don't think he looks tired as he turns his face away from Touya being glomped by Nakuru. I think he looks sad.
But of course, this is CLAMP, and nothing can be taken at face value, and there is much more to Nakuru than meets the eye. And Touya knows all along, just like he knew about Yuki and Yue.
In fact, Nakuru is very similar to Yuki. They are the false form of Ruby Moon, created by the reincarnation of Clow Reed as the equivalent of Yue. Equivalent of Yue, and also his opposite, because Ruby Moon's personality is the complete opposite of Yue's. In a similar way, while Yukito is gentle, sweet and shy, Nakuru is loud and assertive to a fault. The truth is that they're hilarious, and the sort of character that would normally be among my favorites... if it weren't for the fact that they're also a bitch to Yuki.
But I digress. Like the name indicates, Ruby Moon uses the moon's power, just like Yue. The incarnation of Clow Reed, Hiragizawa Eriol, is assumed to be stronger than Sakura (at least at first), so unlike Yuki, Nakuru is in no inmediate danger of disappearing. However, a little extra shot of magic never hurt anyone, and this is actually the reason they keep chasing Touya: they sense his power and wants it for themselves. This is also why they keep interrupting him and Yuki, because they probably have an idea of what Touya is planning to do.
But does Nakuru like Touya? Who knows. They ask about him after he gave up his power, but they seems to have lost interest. Perhaps they accepted that he loved Yuki... or perhaps he was never more than a "delicious feast" to Nakuru. (There is evidence, the first time we learn who Nakuru really is, that they have taken power from others before; but whether it was against their will is something I don't know).
Having said all this, I have a little confession to make. I like Nakuru. A lot. They're one of my favorite characters in fact. I wanted to hate them, but I just couldn't. They're just too funny to hate.
One last thing, which should already be obvious: Nakuru is non-binary. That first time that their true identitiy is revealed, Eriol's other guardian, Spinel Sun (or Suppi-chan) asks they shouldn't be wearing the boys' uniform instead, and uses the honorific kun to refer to them. Nakuru says that they look much better in the girls' uniform, and that since they're not human anyway, gender isn't an issue. So female-presening, canonically non-binary (both as Nakuru and as Ruby Moon). When you start thinking that Nakuru's the equivalent of Yue, and that traditionally angels are genderless... well, that's just very interesting, isn't it?
Yes, you could say I have mixed feelings about her.