Gossamer Axe

An Urban Fantasy novel by Gael Baudino, Gossamer Axe is the story of a "young" woman named Chairiste ni Cummen who was actually born fourteen hundred years ago, and through various magical means has survived into the year 1987. In the sixth century, Chairiste and her lover, Siudb, were captured by The Fair Folk, and trapped in their static, unchanging world for centuries. In the late 18th Century, Chairiste managed to escape with Ceis, the Sidh bard Orfide's best harp, but is forced to leave Siudb behind.

For two centuries, she has tried repeatedly to win back Siudb from the Fey, following the gate to their realm as it made its way around the world, until she ended up in Denver, Colorado. Under the name Christa Cruitaire, she has been passing on some (but not all) of her skills with the Irish harp to students, when one of them decides to pay her back by taking her to an Yngwie Malmsteen concert.

Christa is so overwhelmed by the magical possibilities of The Power of Rock that she throws herself wholeheartedly into Denver's metal scene in order to put together a band and finally defeat the elvish harper to win back her lover.

Tropes used in Gossamer Axe include:

Aerith and Bob: The band consists of Christa, Devi, Monica, Melinda, and Lisa.
Abusive Parents: Devi's father.
Battle of the Bands: The climactic conflict between Gossamer Axe and Orfide.
Blues: Although Kevin is an accomplished rock guitarist, what he really wants to be is a bluesman. However, he feels that his attempts lack something critical. He gains the understanding he needs as a result of his time at Christa's side. And when he enters the Sidh realm at the end of the novel, it's his blues music, not rock and roll, which he uses to heal and change the Sidh.
Cue the Sun: After Kevin enters the Sidh kingdom to bring them change, the sun rises for the first time.
Drugs Are Bad: Melinda falls off the wagon by hanging out with the wrong crowd in order to make connections for the band.
Girls Love: Chairiste and Siudb. Also, Christa and Monica as well.
Magic Music: Which Christa plans to use to win back Siudbh
Not So Stoic: Orfide, the Sidh harper, is a seething pile of bottled-up emotions.
Orphean Rescue: Christa's centuries-long quest to rescue her lover Siudb from the Sidh is exactly this, climaxing in a battle of metal band vs. elven bard to free her.
The Power of Rock: Christa's secret weapon against the Sidh harper
Present Tense Narrative: All the scenes that take place in the Sidh kingdom are narrated in the present tense to show that time does not pass for those trapped within.
Rapid Aging: Without the aid of magic, the years spent in the Sidh world catch up to those leaving all at once. This includes death and decay.
Really Seven Hundred Years Old: Christa spent several centuries not aging at all in the Sidh realm, and has kept her youth with the judicious help of the sapient Sidh harp she escaped with.
Screw the Rules, I Have a Nuke: The basic gist of Christa's response to Orfide's objection that a full band against a soloist is far from an even battle. (Even so, Orfide is dangerously close to a "nuke" all by himself.)
Sentient Musical Instrument: Ceis, Christa's harp, is a sentient creature in its own right, who aids her magic and keeps her young with its own. When she turns to rock and roll, the harp/spirit volunteers to transfer to her custom-made electric guitar.
The Stoic: The elves, with few notable exceptions, do not display emotions at all.
The One Guy: Kevin Larkin, Christa's friend and guitar teacher (though she rapidly surpasses him).
Title Drop: Guess what Christa's band is named?
Year Inside, Hour Outside: Time doesn't pass in the Sidh realm; thus a few hundred years there will be nearly no time in the human world.
Yngwie Malmsteen: Chairiste's decision to abandon medieval Celtic music for Rock and Roll in order to rescue Siudb is inspired by the incredibly powerful magic accidentally generated by Malmsteen during a live concert she attends.