Bob

Bob is a spirit of intellect inhabiting a human skull. He acts as Harry's Lab assistant and living encyclopedia of magic. Bob first appears in Storm Front.

Description
Bob has been assisting wizards since the dark ages. Bob doesn't forget anything, unless he intentionally chooses to do so. Bob has great experience in applied magic from being owned by several wizards, as well as innate knowledge of the rules of the supernatural and their current status.

As a spirit of intellect, Bob is unable to forget anything unless otherwise instructed by his current owner. He is also incapable to make most moral distinctions between good and evil. (ref?)

He is sometimes paid (via romance novels and certain considerations) by Harry Dresden, in exchange for information and magic lore. (ref?)

In Ghost Story, inside the skull, Bob appears as an ordinary looking young man, modestly tall, slender, decent shoulders and looked sort of familiar. He was dressed like James Dean in a biker jacket, white shirt which appeared forced on him. He had an embroidered skull on the jacket over the heart. He probably looks a lot like young Butters.

Skull interior
It was like a James Bond apartment, a penthouse. There was black marble, mahogony, a huge fireplace, the hand-carved hardwood furniture all matched, There were couches, recliners, two chaises, covered in fabric like raw silk embroidered with sigils in gold and silver. There was a table with a huge spread including a turkey, fruits, vegetables, and multiple side-dishes. Behind a curtain was a huge TV, a stereo system, amd multiple video game units.

Personalities
Under Harry, Bob is benign and helpful, if smart-mouthed; however, he is also an enormous pervert. He insists that Harry buy him romance novels as 'payment', and every time Harry lets him out of his skull, he goes out and causes trouble, usually sexual in nature; in Fool Moon, Harry chides him for invading a party and inciting an orgy after Harry gave him a day out, which Bob replies to by saying "I didn't do anything to anyone that a keg wouldn't have done". In Storm Front, Bob is given a 24-hour pass by Harry; at the end of the book, Harry says he "looked the other way" on a party that lasted for an entire day. Every time Molly Carpenter comes to Harry's apartment, Bob relentlessly pesters him to let him talk to her. It's likely that Bob's owner's personality influences his own - if this is the case, Bob's tendency to be smartmouthed is probably a direct trait from Harry.

Under Butters, he acts a lot like he used to with Dresden, due to Butters knowing Harry, basing his personality off that first impression.

Early history
Bob was bound to the skull by Etienne the Enchanter in France in the Middle Ages, during the Inquisition. (book and chapter ref?)

He was later owned by Heinrich Kemmler and for close to forty years pursued dark interests. After Kemmler's death, the White Council Wardens thought Bob destroyed, but he was in fact taken by Warden Justin DuMorne.

DuMorne later left the Wardens, and secretly kept Bob for himself. It was during this time that Bob was instructed (or possibly chose) to forget about his time with Kemmler and the work he did, thus destroying many things and locking away what couldn't be destroyed. Because Bob is a spirit of intellect, and is made of knowledge, losing this information would amount to a human losing a limb, or worse. After DuMorne was killed, Harry Dresden picked up Bob's skull. (Dead Beat)

It was implied that Bob had done something to warrant the wrath of Queen Mab, but it was later found out that it was his knowledge of how to kill immortals instead.

Bob's skull was picked up by Harry Dresden after the death of Justin DuMorne, and it was with him that he was called "Bob" by Dresden.

Bob is able to lend Harry access to his vast mystical experience, often providing vital information about magical objects or rituals or difficult rituals. As a form of payment, Bob often demands trashy romance novels; Dresden theorizes that being a creature of intellect himself, Bob somehow identifies with characters that exist only in the mind and therefore lives vicariously through their actions in novels (although Dresden notes that it was entirely possible that Bob merely looked at them the same way some men look at blow-up dolls). It also seems to help Bob to stave off his more impulsive urges.

In Ghost Story, Bob reappears again, under the control of Butters. The evil piece of himself that he split off from is assisting the Corpsetaker on attacking Mort's home. It is revealed that he looks attractive in spirit form and can literally curbstomp any ghost, wraith, or spirit other than his evil self and Corpsetaker. The inside of his skull is similar to a mansion.

Storm Front
In Storm Front, he helps Harry make two potions: an escape potion and a love potion, the latter at Bob's insistence. Later, when Susan accidentally takes the wrong potion, Harry and susan are trapped in the Lab's circle and the potion kicks in. Harry lets him out so he can throw him the escape potion in exchange for twenty-four hour leave. Bob return after a wild party at University of Chicago.

Fool Moon
In Fool Moon, Bob helps Harry brew two potions, and informs Harry about Therianthropy, Lupine theriomorphs, Werewolves, Lycanthropes, Loup-garous, Shapeshifting, etc. Harry bribes Bob with new romance novels to go on an information hunt on werewolves in Chicago.

Grave Peril
In Graver Peril,

Summer Knight
In Summer Knight, Bob and Harry discuss the hierarchy of the Sidhe Courts. Bob tells Harry that Ronald Reuel was the Summer Knight.

Death Masks
In Death Masks, Harry gets out his copy of the Unseelie Accords to look up the Code Duello in preperation for his duel with Paolo Ortega but Harry can't make out the hight-toned language. Bob gives him the CliffNotes version. They also talk about the plague curse that got that corpse in the morgue and the Eye of Thoth. Harry shows him the drawing of the sigil and Bob freaks, tells Harry to throw it out, burn it. He says they're worse than just Fallen: assissins, poisoners, sorcerers, warriors, the coins make them nearly immortal. Bob can't track down the Shroud, it's an object of faith and not his jurisdiction and suggests he talk to Ulsharavas. Harry sends him out to find what he can about Paolo Ortega and to swing by Marcone's Estate.

Later, Bob returns from his info-hunt badly hurt by wards at Marcone's Estate. Bob reports that Ortega is at the Rothchild Hotel with six vamps and a dozen mortals. It turns out that Gard did the wards. She is Marcone's newest security person.

Blood Rites
In Blood Rites, Harry ask Bob to take Mister out to locate Mavra and her scourge. The next morning, Harry is woken up by Mister, inhabited by Bob, walking over his face. Bob returns in Mister—he went to strip joints instead of sticking to his mission to find Mavra. Harry is not pleased and threatens to break Bob's skull with a hammer until he re-inhabits Mister and goes out again.

Later, Bob returns and reports. Mavra is in a homeless shelter near Cabrini Green. They most likely came from Undertown. Bob draws a map of the shelter and its lower levels. There are people locked on a closet, six Renfields each with a darkhound and the staff are changed into rough thralls. Bob teaches Harry about Renfields and that the White Court had Stoker publish his book to tell people about them. Black Court vampires use mind control magic to recruit Renfields. Bob says that even the original Merlin could not undo a Renfield. Justin DuMorne had done a lot of research on the subject so he's sure of his facts.

Dead Beat
In Dead Beat, when Harry asks Bob to remember what he can concerning Heinrich Kemmler, Bob refused to answer unless Harry let him out for the duration of the conversation. Once out, he warned Harry about the dangers of him accessing these memories. Once ordered to access said memories, he tricked Harry into being tainted with a hint of necromancy, and almost killed Harry before being ordered back into his skull.

Later, he was stolen by Cowl and Kumori  and assumed an alternate personality. It is currently unknown whether he was faking this personality, or if he is forced to become attuned to his current holder. Once put down by Cowl, Harry reminded Bob about how he had Named him, as previous owners had simply called him "spirit", which supposedly freed Bob to help Harry. When he helped Harry, he took over Sue the T-Rex and compared that or any other zombie to a choice between steak or a hot dog.

Proven Guilty
In Proven Guilty,

White Night
In White Night,

Small Favor
In Small Favor,

Turn Coat
In Turn Coat,

Changes
In Changes, Bob looks a photos of a Red Court shipment. He says that they're ritual objects of dark and dangerous magic, which is obvious from angles and the imbalance, they are meant to be destructive. They are meant for Human Sacrifice. The slaughter of an innocent.

Harry takes Bob into the Nevernever with him escaping the FBI Barry Tilly and Rudolph. While there they are confronted by giant centipedes. Harry is forced to go back and be arrested. So, he stashes Bob, the Swords and bag in a hole. Mister was sprawled across Bob's shelf using his paperbacks a a pillow. Harry rub's Mister's ears and promises himself to get Bob back soon, for now, he was safely hidden in a hole in the Nevernever. Lea later returns Harry's bag with Bob in it. In Chichén Itzá, Harry takes Bob out of he bag, shows him the set-up for the ritual Bloodline Curse, Bob tells him what he's dealing with. Bob creates a shield that blocks the power of the Red King, freeing Harry, who then has him follow Murphy to protect her, to his utter delight. At the end, Bob floated out of the P-90 and back into his Skull complaining that it was too close too dawn that Harry got him out.

Ghost Story
In Ghost Story, Butters and Bob save Harry's ghost from a pack of Lemurs eating him. Bob kills the Lemurs then returns Harry's essence to him. Harry rides along with Bob inside the skull. Bob and Harry talk over Harry's situation, and acts as a sounding board for who may have killed Harry. Bob suggest that Harry is the subject of a shell game involving Mab and Uriel. And, He Who Walks Behind was Justin DuMorne's mentor, not the other way around—that Harry was being pushed into becoming a weapon. Plus Harry is running around in his Soul without his spirit. (His theory is that the: "Spirit is the seed and the soul is the earth it grows in.") If something happens to him here, it's for keeps. Harry had a choice, but didn't read the fine print. Bob combatted with Evil Bob in the Nevernever allowing Harry and his ghost-troops to escape and enter the Big Hoods' hideout: Corpsetaker's stronghold.

Cold Days
In Cold Days, Harry broke into Waldo Butters apartment to steal Bob. He fled after combating Evil Bob in the Nevernever. While there, he was attacked by Andi in wolf form—she lives at Butters place now. Harry was trying to give them cover from his enemies by breaking in rather than asking for Bob. Bob revealed that Mab wants to destroy him due to his knowledge of how to kill immortal beings. Bob made Harry promise to build him a new house for the knowledge. Bob told harry about Conjunctions in time and that Halloween is the one on which immortals are vulnerable: they are mortal on Halloween. And it's when they refuel on energy and add power to their mantle. Bob wished Harry a Happy Birthday. The Kemmlerites did their Darkhallow on Halloween. Killing Maeve makes no sense, since the mantle will make the new one just like the old one.

On Demonreach, Bob said the spells on the rocks of the tower were complex and impossible but someone didn't care. Harry and Bob followed the Demonreach Entity down into a deep well on the island where he showed them the Naagloshii and the Dark Gods imprisoned there. Harry is now the Warden of the prison. Bob played a movie for Harry showing The Original Merlin creating the prison in various times but all at the same time, building an immortal jail in three dimensions. The problem: a whole lot of energy hits the containment spell, it will unravel, releasing the nightmare prisoners.

Murphy got Harry to agree to return Bob to Waldo Butters because he's too valuable to let fall into the wrong hands.

Skin Game
In Skin Game,

Quotes
See: The Dresden Files quotes for more.
 * Bob: "It's bad enough that I have to wake up, I have to wake up to bad puns." — in response to Harry saying: "Come on, lazybones." ~ Storm Front. It's the first thing Bob says in the series.


 * Harry wakes up Bob: "What's up, boss?" — "Evil's afoot." — "Well, sure," Bob said, "because it refuses to learn the metric system. Otherwise it'd be up to a meter by now." ~ White Night

Concept and creation
Jim Butcher had this to say about his inspiration for writing Bob:


 * Bob started off as an inside joke between my writing teacher, Debbie Chester, and myself. I needed a device to get the rules of magic across to my readers, so that they would have a point of reference for the laws of my story world. I talked with Debbie about maybe designing a character whose fundamental function was to have conversations with Harry about the nature of magic, so that the readers could all understand what was going on. "Sounds fine," says Debbie. "But whatever you do, don't create some kind of talking head." In story craft terms, a talking head refers to a character whose purpose in life is to dispense information. Talking heads will wander onto the page, blurt out exposition without bothering to display much in the way of character or motivation, and promptly exit. So when I designed Bob, complete with his little obsessions and quirks, I decided to make him a literal talking head, while avoiding the traits that add up to a story-craft talking head.

The idea of the skull itself was inspired by the Scooby Doo splash screen.

Word of Butcher
Jim Butcher has said that that Bob takes on some of the personality of his "master", explaining that Bob is such a smart aleck and into girls because Harry picked him up when he was just 16.