He's an 8-year old kobold orphan who grew up on (and under) the streets of Waterdeep. He was befriended by an unscrupulous mage street performer named Jonas Whisper. Freddie's job during performances was to sneak through the crowd and pickpocket members of the audience. During the time he traveled with Jonas, Freddie picked up some tricks of his own, specializing as an Arcane Trickster. Freddie struck out on his own after three years of serving Jonas. The young kobold made his break after stealing a Cloak of Useful Items, an enchanted short sword, and a Rope of Climbing. He continued his “life of crime”, stealing only enough to survive before eventually finding himself in Phlan.
Freddie always narrates everything he's doing in the third person because he feels it helps him to concentrate. While a mature kobold, he's also not so old as to enjoy a good practical joke, both magical and mundane. This has nearly cost him his life as he likes to watch his schemes unfold.