Hmm...Not likey at all. Keiko really seems to like Yusuke and through out the whole TV show, barely even talks to Hiei.Another big fact that Hiei and Keiko will not be together is that in the last episode, Forever Fornever (right?), Keiko screams out Yusuke's name at the beach. Yusuke (great timing buddy) comes and they embrace, but Keiko kisses him. Awww, is that adorable or what? I bet he was suprised.Not only that, but they did get married, or Yusuke proposed to Keiko. All proof of Yusuke and Keiko's relationship could be found on Spirit Gun.
Yukina
Two words: Brotherly Love. Brother and sister. What more should I say? But yeah, I'm not sure but in some Animes brother and sister get together. Like, for instance, Omi from Wiess Kruez kissed his cousin Ouka...but yeah...*sweat drop* what are we talking about? Oh right, well. I'm just saying, Yukina and Hiei...werid.
Makuro
Eh...not a fan of these two....but still, the facts and stuff. Makuro and Hiei have A LOT in common. Both have dark past, has skills of fighting, and lots more. BUT, it's really like Hiei only thinks of her like someone he can talk to, since they have so much in common. Plus, Hiei is her heir. If she dies, Hiei takes her place in owning one third of Maikai. Hiei and Makuro's relationship is more on the line of, 'you're-my-heir-I-trust-you'. I'm sure Makuro can lighten Hiei up, but maybe Botan can do even more. She can show him how to have even the happiest smile on! XD
Kurama
O_O Well, I just really don't see them together. Out of all of those pictures I see of them together in a romantic way, nothing in my head but noooo! There was this one picture I saw, which was actually not fan-made. Kurama was tugging Hiei's earlobe and Hiei was just staring at you. Some people say that's a sign. I dunno, I tug people's earlobes and I don't even know them at some time. Sometime, I grab on people's shirts when I'm afraid I would fall on the stairs and they are complete strangers! ^_^" I'm afraid to fall. But right, this is about Kurama and Hiei. I think they see each others as friends. Even the creator answered an interview saying Kurama and Hiei are not romanticly involved. That could be a rumor, but I'm just going to have to check it up. I do believe the only reason they are such good buddies is because in the Two shot special manga(which I have seen for myself) Hiei personally seeked out Kurama, who after risking his love, Maya, reluclently joined with him.
Koenma
Hiei doesn't seem to have a problem with Koenma, and Koenma rarely has problems with him. Well, if I was Hiei, I wouldn't want to get on the Prince of Reikai's bad side. Hiei is, after all, a criminal doing his time outside of jail. Koenma pretty much controls his criminal report, and uses it to his advantage. In episode 22, Lamenting Beauty, Hiei delivered the video tape like Koenma told him to, even if he did look at it before he delivered it (I think that's how it went). However, Hiei gets things out of the relationship too. Take this quote, "Koenma, if these fools are done, I have my own question: in what class do you rank me?" Hiei probably uses Koenma to keep track of his demon ranking, and to slowly finish off his jail time. In episode 68, Setting the Trap, Hiei refused to help rescue Yusuke until Botan bribed him with clearing part of his criminal record. So, from as I see it, Hiei and Koenma relationship is nothing more then 'use and get used'.
Kuwabara
Let's start this with a quote, ne?
Kuwabara: "I have the feeling that I'll win!"
Hiei: "And I have the feeling that you'll die..."
Hiei really despises Kuwabara in the beginning. When first meeting Hiei and Kurama, Kuwabara says, "Who the hell is this? Isn't he being awfully rude for someone so short?" so I guess the feeling is mutual. However, throughout the Anime, Hiei and Kuwabara may still insult each other but they have a hidden respect for each other. They do have a friendship hidden under their mean attitude towards each other, but thats it. Some people might say they hate each other to mask their love. O_o I think I'll leave that to another quote (I'm really enjoying them!).
Yuusuke: "Hey, where do you think you're going? Now that your little secret's out, there's no reason to... Look, what I'm trying to say is that I could really use your help on this one. Kuwabara could really use your help on this one."
Hiei: "But I hate Kuwabara."
Yusuke
Some people enjoy this couple, and they use images like Yusuke attempting to kiss Hiei and Yusuke feeding Hiei to prove their point. Hiei is a real brick wall, and Yusuke looks like he's only trying to get Hiei to join into the fun. In both pictures, everyone except Hiei enjoying themselves. Yusuke is just trying to get him into the care-free mood. After all, Hiei respects Yusuke and his powers and Yusuke trusts him. Plus, do I need to get into the Keiko/Yusuke thing again?