Haruhi/Hikaru
The Twins: Part III
Haruhi didn't have nearly the same problem as everyone else in telling the twins apart. Hikaru was slightly more emotional than his brother, Kaoru. It took her some time to notice it though, and was difficult for her to put it into words.
Haruhi thought Hikaru was cute, but no cuter than his brother of course. They were identical twins, how could one be cuter than the other?
Hikaru didn't think much of Haruhi at first. He was an disgusting looking classmate of theirs that never spoke unless it was to answer the teacher's question. His hair was a mess, he wore ridiculously bulky glasses and he didn't even wear the school uniform! Why should Hikaru pay the boy any amount of attention?
So when Kyoya asked about the boy neither of the twins had an answer. And they didn't care that they didn't have an answer. All they needed in their world was themselves.
Haruhi didn't think too much on Hikaru in the beginning because she couldn't tell the twins apart, same as everyone else.