I did some searching and it looks like your quiet little cat could be a 'maine coon'
if so, he won't be 'little' for very long.
The female Maine Coon weighs between eight and 12 pounds while the males can weigh up to 20 pounds. Their bodies can stretch up to 40 inches in length.
Maine Coons are often mistaken for bobcats due to their massive size!
More info HERE