YA Fantasy. Girl/boy gets powers from the sun and gets locked in dungeon

[Trisha]

Don’t remember any characters names just remember girl or boy get locked in a dungeon. She/he escapes through the sewer system with a man and go through a grate like door that she couldn’t fit through and had to figure out how to get on the other side. Possibly escape in carriage to the ocean to the ocean where she has to replenish her powers but it’s a cloudy day and there are ships that come, there’s a fight scene and the sun is going in and out from behind the clouds while there is a fight scene.

Friend is trying to figure out the name of this book and it’s driving her crazy!!!

Thank you in advance!

[Summer]

Do you remember what the powers were? One of King Arthur's knights had magical strength that depended on the sun, I believe

[Diarmuid]

Summer wrote: "Do you remember what the powers were? One of King Arthur's knights had magical strength that depended on the sun, I believe"

yes! sir gawain!

[Robert]

In Dragon Prince, by Melanie Rawn, one of the characters who works magic using the sun gets locked in a dungeon.

[Caroline]

Robert wrote: "In Dragon Prince, by Melanie Rawn, one of the characters who works magic using the sun gets locked in a dungeon."

It was the main female character and she gets sexually assaulted multiple times on the orders of one of the main villains, Princess Ianthe. Then she and her Prince are released after Ianthe drugs the Prince into having sex with her. Not exactly YA.

[Trisha]

She doesn’t know if it was YA or not. Doesn’t recall what the powers were either. I told her sounds like a fever dream lol