In my opinion, Paul Coker was never developed enough to be a "proper" character.
He was given a few personality traits/bits of background (as noted by other FMs) - gay, loves his grandparents, been working abroad, diabetic, confident - but never really explored. I mean why did a young man who is so devoted to his grandparents choose t live and work abroad?
To use the Harry Potter series as an analogy, Paul was as developed as Dean Thomas as a character but then shoved into Ginny Weasley's stories.