Gin

Gin is a member of the Black Organization and a main antagonist of the series. He is the organization member who gave Shinichi Kudo the experimental poison APTX 4869 which turned him into Conan Edogawa. He is frequently paired on missions with Vodka. In the English manga, he was first introduced as Melkior, but later was reverted to Gin. This is likely due to the fact that Conan is often reminded of the Black Organization by references to alcohol.

Of the high ranking members of the Black Organization shown, Gin is the most loyal: he follows the boss' orders most closely and virtually never acts against the Organization's greater interests. He is also one of the Black Organization's most dangerous operatives; Conan miscalculating his intelligence, abilities, and speed of response have resulted in several very close calls and awry plans.

Gin is a merciless and efficient assassin. He has no compunctions about killing or threatening fellow teammates. Fitting his icy personality, Gin's displayed range of emotions so far is relatively limited. Wearing a threatening smirk, he enjoys hunting traitors, watching the plans he has concocted succeed, and cornering his targets. Although he seems to take satisfaction with taking out someone personally, Gin is also satisfied with orchestrating a target's death even if he does not pull the trigger himself. He is not easily frustrated and takes setbacks in good stride, shown when he coolly orders a retreat when Shuichi Akai ambushed the Black Organization and when Bourbon tricks him and wastes his time by disguising as Scar Akai. He is patient and cautious, preferring to wait until success is most likely. He does not like potential loose ends, preferring to get rid of anything doubtful. Gin does not trust anyone and does not fully believe anything he doesn't witness himself.

Certain individuals elicit more of a response than others from Gin. Gin doesn't seem to enjoy Vermouth's antics; he tried to put an icepick through her head after she disguised herself as a waiter to tease him. Gin finds Bourbon, who has several shared characteristics with Vermouth, annoying as well. He has a personal rivalry with Shuichi Akai, and takes interest when the FBI agent gets involved. For uncertain reasons, Gin has an abnormal attachment to Shiho Miyano, so he broke from his normal efficiency-oriented hunting strategy in favor of a more dramatic confrontation with her for his personal enjoyment.

(Source: Detective Conan World)