While Mac does get the lion's share of character development in the 1st season, the show does give Detective Danny Messer (Carmine Giovinazzo) some background shading on the 13th episode "Tanglewood," when his neighborhood knowledge proves invaluable to a case.
The main plot of "Tanglewood" involves a young man, Paul Montenassi, who was beaten to death and then left out in the snow. Mac notices that his body had been tattooed, but the art was forcibly removed. Hawkes finds that his tattoo formerly read "Tanglewood." Danny is himself working a hit and run but is consulted because he grew up in a New York neighborhood where the Tanglewood Boys were a popular gang. Danny notices that Paul was never a real recruit because there were no dates on the ink. He also reveals to Mac that he was himself asked to join them. The future detective turned the gang down, but he sympathizes with Paul's need for acceptance.
In a twist ending, Paul's killer, Tanglewood Boy Sonny Sassone (Michael DeLuise), is caught, but he tells Mac and Stella that the gang and Danny know each other well, to their shock and dismay. The greater implications of Sonny's words, as with a lot of character development on the show, are ultimately explored more in Season 2 of "CSI: NY."
