Both dogs speak with a soft Italian accent, in reference of the Italian Mafia.
They both come off as smooth-talking, mobster-like goons who don't mind playing with their victims. But they can also be violent, vicious, sadistic, brutal, ruthless, thuggish, mean, and downright merciless. This also plays on the stereotype of Dobermans being savage, brutal, and used often as attack or guard dogs.
Roscoe appears to be attracted to Rita, as he tells her in the film, "You know, Rita, I can't figure out why you'd rather hang around a dump like this, when you could be living uptown with a class act like myself." but she is plainly disgusted by him.
Roscoe seemed to be the more cool-headed of the two, while DeSoto is a bit more vicious, shown when DeSoto displayed a desire to eat Oliver (failed), while Roscoe thought it would be better to heed their master, Sykes' call. Also, at the end of the film, while Roscoe simply falls off the back of Sykes' car to his death after accidentally tearing off Dodger's bandanna, DeSoto actually had to be fought off by Oliver in order for him to die.
In the movie, Bill Sykes (who lent Fagin some money) comes by Fagin's home in his car to get his money back from him and sends his two dogs, Roscoe and DeSoto into Fagin's boathouse to tell Fagin to meet up with his boss while they harass Dodger and the gang. Once inside, Roscoe flirts with Rita, while DeSoto sniffs around the houseboat. When Francis insults Roscoe, he loses his temper. Tito tries to fight them but is luckily held back by Einstein, who suggests he picks on somebody his own size. However, Roscoe is not intimidated by him but Dodger waltzes up to him and asks him if he has lost his sense of humor. In reply, Roscoe smashes their TV and says, "See? I find that funny." and chuckles sinisterly.
Just as further unpleasantness is about to ensue and when their master, Sykes, calls for them with his horn, DeSoto finds Oliver but Roscoe tells him to forget it and to go. Nevertheless, DeSoto tries to eat Oliver, who in return, scratches him on the nose, causing the two dogs to attack Oliver, not before Dodger and then the rest of the gang stand in and protect him. Both dogs hesitate, knowing that they can't take on the whole gang. Outside, Sykes honks his horn again outside for the dogs to return to the car and Roscoe and DeSoto leave reluctantly, with Roscoe swearing retaliation; starting with Oliver.
Later, when Fagin goes to talk to Sykes about getting his money from Oliver's owner awkwardly, Roscoe and DeSoto attack Fagin after Sykes orders them to do so with a snap of his fingers, but Dodger leaps forward and fights the dogs, taking severe (but invisible) injuries in the process. When Fagin tells Sykes about Oliver's owner being rich, shows him Oliver as proof, and that they're coming tonight to get the cat back properly and loudly this time, Sykes, convinced, has his dogs pull back from Dodger and tells Fagin he has 12 hours to pay him his money back as his "last chance" when feeding dog biscuits to his dogs while Fagin and Oliver come to Dodger's aid after Dodger lays injured and unconscious with severe (but invisible) injuries from the Dobermans' attack.
After Sykes kidnaps Jenny after they unknowingly watched, in their master's car, Fagin giving up the ransom the whole time, Oliver and the gang secretly follow them to Sykes' warehouse. While Sykes ties up Jenny, he tells her not to cry as Roscoe and DeSoto pace around, growling. Then, he orders Roscoe and DeSoto to sniff around the place for intruders after hearing a noise. When Dodger and the gang sneak into the warehouse, one of the dogs, Georgette, screams because of a broken nail, alerting Roscoe and DeSoto. Later, DeSoto is the first to smell them; informing Roscoe.
Roscoe and DeSoto run into Francis, Tito, and Einstein, who were distracting and luring Sykes away while the rest help Jenny, but just as they're about to attack, Georgette pulls a blanket down on the two dogs, trapping them until Sykes comes along and frees Roscoe and DeSoto. Sykes and his dogs chase Oliver, Jenny, and the gang, who escape with the help of a crane and Tito's electric specialty then fall and land on a long slide after Sykes destroys the crane's control with an axe, through the warehouse but just as they have them cornered and Sykes is about to snap his fingers "again" to order his dogs to attack, Fagin bursts in on his scooter, after hearing a honking noise which is actually his scooter's horn, and the gang flee.
The two evil dogs chase Fagin and the gang on the street but luckily, they are able to outrun them until Sykes and his dogs give chase in his car. When Fagin drives his friends in a substation, Sykes is still able to follow them. In a tunnel, when Jenny gets knocked onto Sykes' car hood, Oliver jumps on and bites Sykes' hand, but Sykes tosses Oliver into the back, where Roscoe and DeSoto are. Dodger manages to jump aboard also and jumps on Roscoe who later grabs a hold of Dodger's bandanna after being thrown out of the car's back window by Dodger. The bandanna snaps and Roscoe falls onto the subway's third rail, which electrocutes him due to the friction caused between the ruined car tires and the rail tracks. DeSoto then jumps onto Dodger and is about to strangle him, but Oliver manages to jump onto DeSoto and scratch him on his nose "again," causing DeSoto to yelp in pain, jump, and fall onto the railway tracks and get electrocuted as well. Sykes is too busy chasing the gang to even notice what's happened to his dogs and shows no mercy for his dogs as he continues to chase the gang until his car runs into a train, killing him in the end.
DeSoto appears in the episode "Pluto Saves the Day" with the Pet Shop Dogs band singing "Everybody Wants to Be a Woof". While singing in the choir with Tito growling at him, DeSoto replies with a growl in return, thus scaring Tito off, which contradicts their encounter in the film. Later, he is seen with the other Pet Shop Dogs fighting off Pete (who's disguised as Snow White) and then chasing him out along with the rest of the dogs and Pluto.
- Roscoe has a similarity to Shenzi from The Lion King: both of them say "Like you?" when the protagonists asks them to pick on their own size (Roscoe: Einstein, Shenzi: Simba).
- Roscoe Blvd. and DeSoto Ave. are major streets in the San Fernando Valley, several miles from Walt Disney Studios.
- The name of the actor who gave the voice of Francis in Oliver & Company is Roscoe Lee Browne.
- Roscoe appears more as Dodger's archenemy while DeSoto appears more as Oliver's archenemy.
- Although both Dobermans look identical, it is unknown for a fact if they're actually related.
- Along with their master (hit by an incoming train), both Roscoe and DeSoto appear to have one of the most graphic deaths in Disney history (more so with Roscoe than DeSoto since the latter's death was only heard from off-screen).
- Roscoe and DeSoto appear as the main antagonists to Oliver and the gang while Sykes is more of the secondary antagonist to them.
- Roscoe and DeSoto are the first two Disney villains to be killed via electrocution (due to them being tossed out of Sykes' car and onto the subway's third rail), followed by Ursula and Jafar.
- The mark left on DeSoto's nose after Oliver scratches it disappears shortly afterwards when the two Dobermans corner Oliver. The mark then reappears after Dodger gets in their way to protect Oliver.
- The characters Cane 1 and Cane 2 (Dog 1 and Dog 2) in the Italian series Slash:// look exactly like Roscoe and DeSoto, even bearing the same colored collars.