On the American Idol season 20 finale, third place finalist Leah Marlene sang a duet of Katy Perry's hit song "Firework" with the judge herself, which suited the spirit of the show to perfection. Leah, a 20-year-old musician from Normal, Illinois, grew up around music thanks to her father, Derry Grehan. He is the lead guitarist of the Canadian rock band, Honeymoon Suite. Her talent and artistry are evident in every song that she sings.

In April 2011, when Leah was nine-years-old, she sang an acoustic version of "Firework" in a talent show, while playing the guitar. She was accompanied by her father, who played the guitar. Fast-forward eleven years later, to the American Idol stage, where the video of nine-year-old Leah singing the first lines of the song played on a giant screen. In a full circle moment, the camera then panned to Leah the American Idol finalist, who took over the melody live on stage, with her dad once again playing the guitar. Katy then joined Leah for an emotional and inspiring duet of the song, featuring soaring vocals and incredible harmonies.

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This performance showcased the essence of American Idol. At Leah's audition, in her bucket hat and patchwork clothing, she was a quirky and talented musician. However, throughout the competition, she transformed into an authentic artist. Watching Leah as a child on screen reminded the audience of how she blossomed throughout the season. She even wrote and released her own single, "Flowers," a song about how people can find their way out of the most difficult times. It is always exciting when the judges duet with the contestants during the American Idol finale, but this particular performance really illustrated how close the relationship between them is. Katy has always been the perfect judge: part cheerleader and part gentle critic. She helped to fine-tune Leah's artistry into something that will help her to succeed in the music industry.

Katy is a pop superstar, but during this American Idol performance, she gave the spotlight to Leah and allowed her to shine. As Katy smiled at Leah while they sang, "Baby, you're a firework," the love and pride that the American Idol judge felt for Leah was evident. Katy proved that Leah was in good hands with her as a mentor, as she believed in her and encouraged her throughout her entire journey. It was an emotional and magical moment when Katy pointed at Leah while singing the lyrics, "It's always been inside of you. And now it's time to let it through." This reminded Leah that she had always been a star, and showed her that it is now time to make that nine-year-old talent show contestant’s dreams come true. It was a fitting send-off as Leah is ready to spread her wings and fly.

As Katy and Leah hugged at the end of their American Idol performance, while smiling brightly, their admiration and respect for each other could be felt by everyone. Their duet of "Firework" made the audience contemplate the purpose of the competition, which is to find the next music superstar, and appreciate just how big of a role the judges play in achieving that goal. It was one of the best moments in the show's history. Katy discovered Leah, who was already a firecracker, and helped to light the fuse for her so she could become a whole fireworks show. That is what American Idol has always been about.

Next: American Idol: Katy Perry’s Disney Night Costumes Through The Years

Source: American Idol/YouTube