These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Which is ironic because after the manga finished, Rui/Tsukushi became the Fan-Preferred Couple for some who thought Tsukasa became an incredible jerkass at times who kept upsetting Tsukushi while Rui gradually became a much more friendly and warm young man who was always there for Tsukushi.
Makino also occasionally gets awestruck by particularly beautiful girls, even going so far as to decide to attend Eitoku due to being so impressed by Shizuka.
Life Imitates Art: The actor and actress that portrayed Domyouji and Makino in the drama adaptation, Jun Matsumoto and Mao Inoue, have similar personalities with their fictional counterparts. Their relationship off-set developed in a curiously parallel route as Domyouji and Makino's — they started of with bad impressions of each other, Jun tried to win back into Mao's favor, Mao was in love with someone else at the time (apparently she had a boyfriend during HYD filming), two years passed and finally Jun won her heart during the filming of HYD:F movie. (They have not admitted their relationship to the public, though there have been couple sightings and matching clothes going on between them.)
In interviews they flirt and bicker all the time, which have strong vibes of Domyouji/Makino's dynamics.
Unfortunate Implications: Tsukasa is a pretty horrible person at the beginning of the series, although he's been toned down in pretty much every successive adaptation. In all continuities however he's at least introduced as a violent, unabashed bully. In the manga he sexually assaults the heroine. Even as the series goes on, he still does extremely questionable things and is exceptionally violent.
The Woobie: Poor Rui. He was diagnosed with Asperger's syndrome ever since he was young and had great trouble socializing and making friends. The girl who helped bring him out of his shell and first love, Shizuka ends up marrying someone else. His second love, Tsukushi whom he loved more than Shizuka and would stand by with and comfort in times of need ends up with his best friend and jerkass, Tsukasa. After these two rejections, he ends up all alone like he used to be but the manga hints that he may find someone special one day. They don't say anything else about it though, heh.