Deeper: For the longest time, they have only seen the surface of the other. Now, when they have taken the chance to look deeper, the mutual dislike is difficult to hold onto.
Angel: With his silver hair, pale skin and lilac eyes, Kaname sometimes thinks that Zero must be what and angel looks like, a grumpy, sarcastic, tattooed, pierced, ill-mannered angel, but an angel nonetheless.
Demon: Zero has always known that in a political arena or fighting that Kaname was a demon, but he's rather forgotten that it would easily correlate to bedroom situations. Not that he's complaining.
Drug: Zero says that his blood is like a drug; he always wants more than is healthy for either of them and can't go for long without it. Kaname grins and tells him that must mean that Zero himself is a drug. Zero pretends he isn't blushing.
Holic: Workaholic describes both of them depressingly well.
Beat: Which is why Kaname lets Seiren threaten to beat him if he doesn't go home soon.
Sugar: Kaname was amused when he discovered that the reason Zero doesn't like sugar is that it turns him into a hyper, talkative, male version of Yuuki.
Nightmare: Zero is surprised at how easy it's become to soothe Kaname out of his nightmares.
Orchid: Zero always finds an Orchid somewhere in the house every morning when he wakes up.