Iron Man has a soft side. Robert Downey Jr. said he acted as a “den mother” and mentor to his fellow actors on the set of the upcoming summer blockbuster Avengers: Age of Ultron.

“I am an assistant den mother for [Joss Whedon] — we’re more contemporaries,” said Downey at the London premiere of the movie.

“With some younger talent, they’re very exuberant; I remember when I was that way. I kind of feel like I’m the assistant principal,” added Downey.

Downey was a protective co-star to fellow actors Scarlett Johansson (Black Widow) and Chris Helmsworth ( Thor). Downey reprises his role of Iron Man in the Avengers sequel.

Downey has long overcome his drug-addicted days in the 90’s. He is now a bona fide movie star with his success in the Iron Man movie franchise. Downey opened up about his transformation in a recent interview.

“What’s really fascinating to me is that when I was a messed-up guy in my twenties I could never have imagined myself as a comfortably married action movie guy in his forties raising young children and having this very mellow life,” said Downey.

Downey also explained how his work in movies like Avengers: Age of Ultron helps him stay sober. “My work helps keep my focus and I pour as much of my energy into my life as I can and it all reflects back on me and that’s my way of getting high now. I don’t need anything else,” said Downey.