Sidhe Knight

A Sidhe Knight is mortal and a champion of either Sidhe Court, the Summer and the Winter.

Description
There is usually only one Knight per court at a time. The Knight is the only entity allowed to act in affairs that aren't directly related to the Sidhe. If the Faerie Queen wants an outsider dead, he's the trigger man because a Queen can't personally kill anyone not in their court.

The knight works for all three of the Faerie Queens of their own court having different duties with each one: Lady, Queen, Mother.

Knight's Mantle
The Knight gets powers in line with his court. They come from the Queen and go back to the Queen when he dies. They are considerable and "carry a weight that only a free mortal can possess". The Mantle, or power, is key in maintaining balance between the Faerie Courts.

Powers and abilities
It's hard to kill a Knight. Among the Sidhe, it would have to be another Knight or one of the Queens. For a wizard to kill a Knight he'd have to be brawny and have a lot of preparation and a good channel to him to make it look like an accident. For regular people to do it, it would take a burning a building or making a crater, something big.

In Changes, immediately after becoming the Winter Knight, Harry Dresden has access to Winter Ice for his spells. Harry also gained speed, agility, and strength.

Summer Knight
In Summer Knight, Ronald Reuel, the Knight for the Summer Court has been killed and Mab wants Harry Dresden to find the real killer and return what was stolen from him: the Knight's mantle, his power. Harry's suspect list counts eight: the six Faerie Queens, the Winter Knight and Elaine Mallory.

The Knight for the Winter Court, Lloyd Slate, turned traitor by siding with Aurora, the Summer Lady, and killed Ronald Reuel at her behest.

The new Summer Knight is Fix, chosen by the new Summer Lady, Lily. Both are friends to Harry.

Changes
In Changes, Harry is made the new Winter Knight by Mab after he sacrifices Lloyd Slate on the Stone Table.