Look, call it a lack of imagination, but I am struggling to make a backstory for a glamour bard.  I have no idea how to motivate them, I have no idea where their magic comes from, and I have no idea what to do with them.   I love them mechanically, and I love the David Bowie vibe, but I just don't know what to do with them.  Help?

1) Leannan is an eladrin who has always been fascinated with music. She learned her craft from the fantastic birds and singing orchids of the Summer Court and so her music is wild and untamed, meandering like a burbling brook and clear as a crystal bell. She adventures into the Prime Material plane because she is fascinated by the lives and desires of mortals.

2) Aidan was taken as a child by an Annis hag who fed him sweets and taught him to sing. In her guise as a kindly old woman she whispered to him that people were only as good as they could be of use and that they were as simple as sheep. She tutored him in the secret melodies that could twist minds and beguile the senses. Before she could tempt him to any greater evil, however, she was killed by a a group of adventurers who 'rescued' him. He still isn't sure if what his 'nonny' told him was right, but .. it couldn't hurt to find out, right?

3) Waterdeep is one of the most metropolitan cities in all of Faerun. One can find visitors from every nation and even from various other planes of existence. Such a wealthy and decadent city has a great demand for entertainment and houses a Bardic College that boasts students who have made their mark performing all across Toril. Violet has a dream that she will one day perform music that will bring entire kingdoms to their knees in awe and that dream starts with gaining admission to that college.

Glamour Bards are essentially bards who are exceptionally charismatic...their mere presence fills people with awe and inspiration.

You could form a backstory from the subclass description where they encountered a creature from the Feywild...or, perhaps they are just so adept with magic that they've used it to change their appearance to become more beguiling.

A good example of this is Yennefer from "The Witcher" Netflix series (just as a visual aid):

She started as a hunchback; and due to some enchantment from the mages of her order, she allowed herself to be physically changed into a figure of beauty...at the cost of having children. She now seeks magical ways to regain her fertility.

Now, I wouldn't say copy this backstory...but a good idea is: "Did the bard pay a price for their glamour-abilities?"

Maybe they struck a bargain with a hag, and their glamour-powers are only temporary...unless they gain, say, the spell "Wish".

Once, my DM ran a campaign where a minor antagonist was a Glamour Bard whose rich family was reduced to ruin; and forced to live on her own, she developed her enchanting-powers to survive and gain wealth from her idolaters. She may-or-may not have gained these powers from an eldritch spirit, giving her a psychic-bent to her abilities.

"Divinity: Original Sin II" has a bard character named Lohse who is famous and beloved...but she is being posessed by dark spirits that cause her fans to riot violently. Maybe your glamour-abilities let you draw from fey-spirits...but not all of them are kind.

I played a Glamour Bard who was a storyteller who also happened to be a spymaster...and their Mantle of Inspiration was them allowing their allies to position themselves into tactical positions.

Maybe the Glamour Bard is a revolutionary or anarchist...getting those around them psyched-up to overthrow an oppressive empire or tyrant.

Yeah, I am a big proponent of reflavoring things. I don't think a glamour bard necessarily has to have anything to do with the Fae, they just have to use their performance to entrance and beguile. I think they are kind of the bardiest of bards, along with the Lore bards who are more like old world traditional bards.

I forgot to reply to these, but I wanted to thank you all for your thoughtful responses.  These ideas are fantastic!  I ESPECIALLY love the idea of turning him/her into a pseudowarlock!  That's an amazing idea!

Quote from Arcturos >>

I forgot to reply to these, but I wanted to thank you all for your thoughtful responses.  These ideas are fantastic!  I ESPECIALLY love the idea of turning him/her into a pseudowarlock!  That's an amazing idea!

 I'd very much recommend a connection to the fey, in either a patron form or just a teacher. The chaotic and manipulative nature of Fey make for great tools for the DM to use for and against you. 

Also, I like to apply motivators to my characters, a sort of overarching reason for everything they do, something that they have to go after, but can never get enough of. I find Power, Money, and Fame work as great motivators. Glamour Bards who seek ever increasing levels of Fame but are never really satisfied make for fantastic adventurers as they will take on risks that any sane person would back away from.