As strange as it may sound, portrait photography is not as simple and easy as it sounds.
I believe that in order to make a good portrait you need to provide the subject with a comfortable environment and let them know that you are not judging them behind the camera (because that's something that people who aren't used to being photographed feel like).
That's why this particular photograph means so much to me; because even though it was literally the second person in my life I photographed, it felt just right, not only for me, but also for the subject.
In my opinion, this image succeeds as a portrait because it really does catch the subject's essence, his charisma, modesty, good humor, and most importantly, his confidence when being in front of the lens after spending some minutes chatting and talking about videogames and some good poses for the session.