Fix

Fix is a changeling under Winter Court rule. Later, he becomes the Summer Knight. He first appears in Summer Knight.

Summer Knight
In Summer Knight, he is first seen in a photograph in Ronald Reuel's apartment. In Reuel's photo, he's small, slender, copper-sunburned skin, and his blond hair was bleached out by the the sun. When Harry Dresden saw him in person at the funeral parlor, he is a small skinny man with white-blond hair and a dark tan. He was wearing a brown second-hand suit and a clip-on yellow tie, has a dark tan and blond-white hair.

Fix seems to be nervous and twitchy, kind of shy and lacking in confidence—not so brave, at least on the outside. Yet when he take his tool box out of the van, he lifts the heavy, bulky box like he does it all the time, with comfort and confidence, implying that he may be a handyman or mechanic.

As the new Summer Knight, Fix's hair is fizzy white floating around his head. When they go to visit Harry Dresden, he has grease on his hands and face and had his old tool box with him on the ground.

Proven Guilty
In Proven Guilty, Fix has grown from about five foot three to about five nine. Harry remembers him as scrawny with spiky hair and equal parts nervous and cheerful. Now, instead of wiry, he's lean cable and his hair is now the shoulder-length style of faerie nobles. Now he projects confidence and strength like light from a star. A pine & honeysuckle breeze rolled in with him and the light appeared brighter after reflecting off him. Harry thinks of him as a thunderstorm in blue jeans.

Small Favor
In Small Favor, he is a young slender man of medium height. He has very fine silver-white hair. He wore jeans and  a green silk shirt, only. He doesn't have the beauty of the fae, but he has a confidence that gave him a certain appeal; a far cry from the nervous scrawny kid of a few years earlier. The snow was falling thickly but not one flake landed on him, all falling to the ground around him.

Summer Knight
In Summer Knight, he went with Harry and the Alphas to find Lily and stop Aurora. He is enraged when Ace kills Meryl, and fights alongside Dresden. When Dresden fights against Slate, Fix attacks with a wrench. Being made of steel, the Winter Mantle is useless to protect the Winter Knight, and Fix breaks Slate's wrist before beating him unconscious.

After the battle, the new Summer Lady Lily appoints him as her Knight. He appears embarrassed by the admiration Lily and Harry show for him.

Summer Knight
In Summer Knight, Harry finds a photo of Fix and his changeling friends with the murdered Summer Knight, Ronald Reuel at Disneyland, putting Harry on their trail. At the funeral parlor, Harry hears Fix and his friends talking in a private room; they know that he's there and are worried about what to do. Fix says that Harry is supposed to be a decent person, but Ace comments that Harry kills people who get in his way. Later, Meryl and Fix await Harry at his car. Meryl apologizes for earlier and that she and Fix want Harry to find Lily.

Later, Fix and Meryl go with Harry and the werewolves into Faerie to stop Aurora from killing Lily on the Stone Table. After Lloyd Slate wounds Meryl, Fix fights him with the cold steel of a monkey wrench until Slate goes still. At the end, Fix and Lily visit Harry at his apartment. Lily is the new Summer Lady and she named him her new Summer Knight. Lily arranged for brownies to clean Harry's apartment and Fix just finished repairing Harry's car.

Death Masks
In Death Masks, the rope that Harry uses on Susan to restrain her when she's near the point of losing complete control of her vampire side came from him. He says it's Faerie made and has the hair of a Unicorn woven through it.

Proven Guilty
In Proven Guilty, Harry meets Fix and Lily at McAnally's. Neither are free to talk, Queen Titania put a compulsion on them to prevent either from helping Harry. Fix gets around it by speaking in theoretical terms about why Summer has not responded to the Red Court encroaching on their territory. Fix insists Lloyd Slate didn't know what would happen to him. When Maeve comes and acts her like usual self, he tells her to drop the "Evil Kinktress" act.

Later, Fix and Lily help Harry, Charity Carpenter, Thomas Raith and Murphy enter Faerie near Arctis Tor so that they can rescue Molly Carpenter. He tell Harry that the battle between the Wardens and the Red Court is going badly and that Summer cannot help because Mab's forces are at their borders. Fix helps them re-enter the rift to the mortal world.

Small Favor
In Small Favor, Fix confronted Harry and Thomas Raith with a shot gun, unsure if Harry had taken up the Winter Knight mantle. Harry was hurt by this action stating: "Friends don't point guns at friends" but understood Fix's worry. As they are leaving Fix says, remember Lily's leaf pin. A little bit later, Harry figures it out that it was the only way that Fix could get past the Titania's geas that keeps him from giving any information to Harry. And, that it was a warning about the leaf pin itself, that it probably has a tracking spell on it.

Cold Days
In Cold Days, Fix confronts Harry Dresden on the latter being Mab's hit man; Harry has to leave town or face him in combat. He also informs Harry that their purposes are different; the Winter Knight follows the commands of the Queens of Winter and kills on their orders, while the Summer Court is meant to stop the Winter Knight.

Later, on Demonreach, Fix still believes that Maeve is trying to help them. Harry tells him that he's wrong, but Fix will not disobey Lily. Harry realizes that as a changeling, Fix had been terrorized by Lloyd Slate, and had to watch helplessly while Slate tormented and raped Lily. For years he had longed for the power to finally stand up to the |Winter Knight and protect Lily; now that he could, he would fight to the death to protect her from any threat he saw.

Fix asks Harry to turn back and not fight him, and Harry asks Fix to stand aside. Neither can back down, and they fight. Taunting Fix and insulting Lily, Harry is able to enrage Fix into attacking first and drives a nail into his shoulder, blocking the power of his Mantle. Harry defeats him but doesn't kill him, and Fix realizes that they've been lied to; Nemesis infected Maeve, and is trying to destroy the world.

When Maeve murders Lily, Fix is devastated, and kneels in grief beside her body crying.