In Keep The Peace, Part II, after Sam is unable to defuse his bomb, Scarlatti is reminded of how he lost Lou and very nearly loses his ability to focus on the task at hand.However, when Sam calls in as unharmed, Scarlatti's determination to stop Marcus Faber redoubles.
He comes off as the 'baby' of the team, even though he's got years of experience of being on the SRU over Sam Braddock and Rafik Rousseau.
Though Scarlatti and Sam start out as distant colleagues, they grow closer over time.
Their friendship never runs as deeply as Scarlatti's friendship with Lou, but they become close enough that in Episode: Blue On Blue, when approached by Sam's sister Natalie for a relationship, Scarlatti decides to let her down easy in order to avoid jeopardizing his professional and friendly relationship with Sam.
In One Wrong Move, Scarlatti tries to save Lou's life when he steps on a landmine but is unsuccessful as Lou decides to sacrifice himself in order to keep Scarlatti from endangering himself any further.
Lou's death had enormous adverse effects on Scarlatti, as seen in several episodes following his death.