Queen Frieda is the daughter of King Victor, and a recruitable NPC. She is a strong Swordmaster and has the ability to open Sealed Doors that would otherwise require the Key of Seals.
Frieda is often found after the 500km mark in an obsidian castle, locked in a jail cell. The player may free her by breaking open the wall or door, and can spend one Charisma level to recruit her to their side. If the player does not have the requisite Charisma, she may reappear in an identical obsidian castle later on and the player will get another chance to free and recruit her.
You can raise her affection by killing monsters with her. Should you raise her affection enough she will open up to you and tell you a little about herself in several events.
If you beat the game with Frieda in your party after her third conversation event you'll get Queen Frieda's Letter, which is an accessory that grants more experience per kill.
Should she die after going through all her events, drops an infinite use item (Queen Frieda's Arm) of one weight that opens Sealed Doors. Cannot be vaulted.
One Way Heroics Plus Changes
In One Way Heroics Plus Frieda gains an additional ability at around 200 affection that allows her attacks to deal combo hits when she attacks at a 50% chance.
This article contains plot details about an upcoming episode.
To get Frieda's specific ending, you must defeat the Demon Lord with Frieda still alive after having three conversation events with Frieda and having Frieda have the highest affection of any party members.