This is the fantastic miniseries that inspired the Sonderberg film "Traffic" (2000). I saw the Hollywood adaption first, but I don't think I'm on my own when I say that they did the original justice. It's all about the sale of illegal drugs through the lives of a vast variety of different people.
In Traffik (1989), Ronan is Lee, a heroin dealer who plays a pivotal role by introducing Caroline to the scene. (If you haven't seen the mini or the movie, get your hands on whichever is closest.) He's not your usual scum of the earth dealer however... I mean, this isn't "Trainspotting" for God's sake (though that is a very good movie). Lee is just a guy who picked up a habit and now is paying for it. Always chipper and always heart breaking.
"I could have gone to university… but I left school early to study amphetamines."
"Women are the worst. They're fucking crazy."
"If you got a habit you either steal or deal. There's no other way."
(while shooting heroin into his pelvis) "It’s the only place where I've got any veins left."
"Good luck. I wish someone was looking for me."