A wonderful character breakdown for Luca, complete with a video explaining just about everything about him in 107 seconds. Nothing I could write for this page would ever be this perfect, without ripping that page off. So, take a look.
Behind-the-scenes: "The Duel" (episode 04.05)
This video is really interesting. It's also nice to see Cillian Murphy and Adrien being friendly with each other in the teaser image. Quite a difference from Tommy and Luca.
How to do an impression of Luca
This is absolutely fantastic. It also highlights the fact that Luca's voice was very much an impression of Marlon Brando's Vito Corleone ("The Godfather") at first. Adrien evolved it a bit as the series went on, thankfully. *chuckle*