Hmm...

I like your coloring job, as well as the fact that for some reason, the eyes and hair reminds me of Square Enix- which I LOVE!! C:
I noticed a few things that you might like to practice on, one being head shape/size. I used to do this too, it was a tricky habit to break- If one makes a person's hair too small or flat (which I can kind of see in the shorter character), it makes their face look too big. However, if one makes it too big then they look like aliens. The trick is to draw the head shape first, don't be afraid to do layering to get things right (DaVinci would layer his paintings from the bone).
Another thing I would like to suggest is differentiating genders. I know that in yaoi, it's important to add a touch of feminine qualities, but I had a little trouble figuring out which was which. Remember- girls have softer features, when you give boys pouty lips and soft jaws, it's a little harder to differentiate. I know how annoying it is to explain to people what gender a character is, been there done that.
Long review is long, but I hope it made sense, and more importantly, I hope it helped. I also hope you continue to do well and to grow even better with time! :D

-Interstellar S.