One of them is a 10’ Shire stallion who was born into slavery. He has a severe disrespect and personal vendetta against anything to do with slave ownership (due to his sister’s death at a slave owner’s hand), and took the name Slave Driver to keep himself in constant remembrance of his sister, as well as a warning for anyone who gives him the “slave” derogatory comment.
The other one is a 4’1” human man. Scrawny, but good humored. His name is the Jockey, appropriately named for his past career as a race horse jockey. That was, until he got caught soliciting drugs (steroids) to intelligent horse athletes as well as participating in rather shady animal fights and deals.
The only one in the posse who actually has a clean and clear past is The Rat, a rodent who isn’t even a rat. He’s a banker, and only got into the gang life to keep himself from dying (as well as keep his family alive to some extent). He’s a rather good natured gentleman and doesn’t live up to his name, people just thought it was funny to name a rodent ‘rat’ despite his actual species.