A portion of a Nintendo Life interview with voice actor, Matthew Mercer...

NL: Did you have any specific inspirations in developing Chrom's voice?

MM: Mainly, I wanted to maintain a balance between casual, cool, stoic, and occasionally playful. He's young, but has a good head on his shoulders and is willing to accept the challenges he's had thrust upon him. Keeping him a character the player can both identify with, and vicariously enjoy his heroics. It was a challenge, but one I was up for.