If Harry has blue eyes like his mother’s eyes, the man with brown eyes is not his father.
I think he looks just like his grandfather.
Don’t be so sure. As long as they don’t have a “BB” Brown rather than a “Bb” Brown, and the other parent has “bb” Blue, there’s a 50% chance their eyes will be blue. My parents were both “Bb” Browns and I came out a “bb” Blue, which is a 25% or less chance.