I found these pictures floating around the internet and they were very close to how I envisioned the characters.
I don't know who any of these models are, but I assure you that no copyright infringement is intended (if they are copyrighted photos), and if any of these models object to them being associated with The Firefighter and the Marine or this blog I will immediately remove them.
That being said, here they are in all their beautiful glory.
Firefighter Kenny Whitfield
Jeff Whitfield, professional soccer player, Kenny's older brother, fraternal twin to Riley Whitfield
Riley Whitfield, actor, singer, musician and professional model, Kenny's older brother, fraternal twin to Jeff Whitfield
Kim (Whitfield) Jackson, oldest of the Whitfield siblings, pediatric oncologist
Firefighter Aiden Montrose, Kenny's best friend
Kelly Montrose, Aiden's wife and Director of Medical Records at the local hospital
Firefighter Teri Richmond, Kenny's other best friend
Captain Thomas Bartlett, Kenny's station chief
Firefighter Tyler "Treetrunk" Daniels, Kenny's boyfriend from his first posting
Firefighter Scott "Tank" Robertson, Kenny's close friend from his first posting
Billy Jamison, forward on Jeff's team
Jimmy Thompson, defender, captain of Jeff's team
Matt Alexander, midfielder on Jeff's team
Firewalker, Kenny's Cherokee brother
Running Elk, Kenny's other Cherokee brother
Lance Corporal Steve Martinson, the Marine Kenny rescued
Gunnery Sergeant Matthew Wilson, Steve's boss