As part of his backstory, Chalmers knew Vic Fontaine when they were children living in south Philadelphia. Fontaine claimed their rivalry stemmed from him always beating Chalmers at stickball. Chalmers became known as "Frankie Eyes" as he would never "miss a trick".
In 2375, although it was the 1960s in the program, Chalmers appeared in Vic's lounge with his enforcer Tony Cicci. With money from mob boss Carl Zeemo, Chalmers had bought the hotel where Fontaine performed and forced him out. Chalmers also used his connections to get Fontaine "blackballed" from performing anywhere in Las Vegas.
Several of Deep Space 9's residents planned to get rid of Chalmers, and after Julian Bashir talked to Felix, they realised they would have to do it as it would have been done in the 1960s. Not wanting the mob to retaliate against Vic if they killed Chalmers, they planned to steal money from the casino so Zeemo would "remove" Chalmers. While Kira Nerys kept Chalmers busy, the others distracted the guards and managed to steal a million dollars from the casino safe. Chalmers and Cicci were led away by Zeemo's men and Vic's holoprogram was restored. (DS9 episode: "Badda-Bing, Badda-Bang")