Growing up Harry had few respite from his cousin Dudley, probably the one that was his favorite was Choir, Dudley hated standing still, hated being seen by teachers and hated staying after school, all things Harry learned to love. It also helped that he was a good singer, good not great or amazing, but surprisingly good for a a boy of only 7. And for years Harry would learn and get better, falling in love with the magic that is music, indulging in a half busted walkman Dudley thrown away and as many pairs of working headphones as he could find, Harry became a music lover.
When he got to Hogwarts Harry lost his connection to music but gained something more, one night in his first year clad in the Invisibility Cloak gifted to him by a Mysterious benefactor Harry delved into the library and in it he found a small tome, rather new but it's spine still stiff. "The Magic of Magical Music" by B. Sharpe lead singer of the Whompping Willows. In it Harry learned many a spell and charm for musical instruments, vocal charms allowing a singer to expand their Range both temporarily and with training forever, even how to create sounds and effects on instruments, effects only seen in the muggle world. While learning these spell Harry over the years would add to his private band, classmates and upper and lower class men as they went.
Neville Longbottom Pianist and Keyboardist had taken to the modulation of pianos like a monster even with his 'weak magic', Anthony Goldstein became the Drummer a skill his parents desired him to learn as a child became a passion, and Harry and the Band became the outlet, Luna Lovegood, Lead Guitar and Backup Vocals.
It was supposed to be a bit of fun, a way to keep the days passing without boredom, that is until the Yule Ball and Kirley Duke lead singer and lead guitarist attempted to fist fight Hagrid while high on Pixie Dust and a Handle of Ogdens. With no band to play, Harry and his band steps up with their covers of Muggle songs turning the Wizarding world on its ear. And with the performance a major change in Hogwarts. (Basically Harry ends up forming a band and by 4th year they are pretty good playing just for themselves in classrooms while covering Muggle songs of various genres and styles from Pop Punk, to Funk, to R&B to general Pop. This causes a stir as Harry is surprisingly a good showman and lead singer, his dedicating several songs to various girls has put him in a series of hot water with various angry Boyfriends and even hotter moments with the girls.)
Final Pairing is up to you, when Hogwarts starts is also up to you if you wanted to do some Lemons and Limes. Just have a variety of songs they sing, a good number of love songs and have fun.