Part of Mr. Brien's new job is figuring out how to make Interpublic's media-agency assets -- which include Universal McCann, Initiative and Magna Global -- work together more successfully. A month after he took the job, Mediabrands was already announcing a deal with ad-technology company Navic that will help marry audience-behavior data with real-time viewership reporting and ultimately improve media-investment strategies.
"He's a man who transcends media. He's a maven in the broader context, a renaissance man," says friend Paul Woolmington, founding partner of media boutique Naked.
Mr. Brien, 46, is busy fostering team spirit by tying staff remuneration to the success of all Mediabrands agencies. He likens the model to that of the tennis-playing Williams sisters, explaining that the only time for fighting is when everyone else is out of the picture.
It was at Universal McCann that Mr. Brien proved himself as a turnaround artist. The first thing he did after taking the risky position of CEO in 2005 was to close the door to new business until the agency had enough top-tier talent to compete effectively. By 2007, he was able to pull off a coup, retaining Johnson & Johnson's estimated $3 billion account through the creation of a new agency model for the client.
"The most fundamental thing we did was embrace radical reinvention," Mr. Brien says of the win. "We not only created a couture operation but partnered with [sibling agencies] R/GA and Momentum and built an agency model that was so customized and progressive it was a game changer."
The son of a German mother and Australian father, Mr. Brien describes himself as "extremely competitive," saying good management is about "bold decisions, making bets and taking calculated risks."
He joined struggling Universal McCann from the relative comfort of Starcom MediaVest Group, where he was chief of Publicis Groupe's nontraditional assets at Arc Worldwide. "I like to build and fix," Mr. Brien says. "I get bored just managing."
Outside of work, he describes himself as a history and biography reader and a lover of the arts. His latest read is "Memoirs of Hadrian," about the Roman emperor.