The two Harlequins players have known each other for some time after playing together in the club's academy and Brown believes that it has always been clear his team-mate would go on to big things.
After a top performance from the flanker in England's 12-6 victory over Ireland at the Aviva Stadium in Dublin on Sunday, the 27-year-old expects the real test to come when they take on France.
England are the only side still in with a chance of securing the Grand Slam following wins over Ireland and Scotland.
But Brown feels that although France are yet to pick up a win in this year's Six Nations, they will be hungry to cause an upset.
"Chris has stayed the same person, even with the captaincy. He still works hard and is a brilliant leader and does for England exactly what he does for Quins," he said.
"When we were in the academy we were asked who would we pick as a future captain and we all chose Chris. Now he's England captain.
"France haven't had the best of starts, but they're a brilliant team who on their day can beat anyone in the world."