Diamond Jack Flanagan is a professional gambler, “owner” of Filbert's Shipping Warehouse the illegal casino in Crime Alley, and crew chief of the Slick 14's crew of The Wound Ravens.

He is a major earner for the Ravens and has a lot of pull in the gang. However, he doesn't like getting his hands dirty with anything other than gambling and spreads money around to other crews to get them to do his dirty work and to pile up favors. He is however terrified that Totally Mental McMurray will turn on him, and has numerous escape plans, stashes and safe houses prepared.

Diamond Jack nurses a strong hatred for 2 men, and acting against them is probably the only time he'd like to take direct violent action with his own hands. One is Earl Atkins of the All Americans gang, who has robbed him on numerous occasions. The other is Hedley Lamarre III, the city relief commissioner who had Jack's mother's house condemned and bulldozed (possibly at the orders of the Falcone Family, possibly for his own crooked real estate scheme).

Jack is friendly, sociable, but never lets a sucker get away without a good fleecing.