Actually, it was the other way round. It was young Vito persuading Signor Roberto to let the dog stay before Roberto asked for information about him. Never mind.
Yes, but the same line is repeated by Signor Roberto, when he goes to see Vito in his study: "Il cane può restare....ma certo che può restare!" I thought you were referring to that line, there were two possible answers.
A. Don Ciccio to Vito, before being killed.
Q: 'A stessa storia 'n antra volta!
"...Brucia la luna in cielo, e io brucio d'amore..."
