David Cook's Heartbreaking Return to Performing

David Cook started singing a slow song, stopped and turned away from the audience

"It's gonna be tough for me," the Idol champ told the crowd of 450 at the Musica theater in Akron, Ohio, on Friday night. "Hold on. I'm sorry. Do you mind if I sing a different song?"

Taking the beat up a notch, Cook then energized the crowd, who passed up flowers and cards and held up signs in honor of his brother, Adam, who died May 2 at age 37 of cancer.

It was a night of emotional extremes for Cook, 26, now back on tour after Adam's death. Speaking of his brother throughout the night, he struggled through some songs – even walking out in the middle of one of them – but exhibited swagger on others.