The woman known as "Jack B. Badd", and "Kyra" was a runaway and convict. When the Hunter Gratzner crashes on the planet, M6-117, she and several survivors, led by Carolyn Fry, are confronted by certain death at the hands of the planet's inhabitants the Bioraptors. During that time she befriends the criminal Richard B. Riddick, coming to admire him & bolstering her courage by emulating him. Shortly after they escaped M6-117, they are captured by a Mercenary ship commanded by Antonia Chillingsworth. There Jack demonstrated a worrying possibility of becoming a killer like Riddick, forcing him to separate from her. Five years later, Kyra is a convicted murderer and former mercenary when she reunites with Riddick. During the fight against the Necromonger Empire, she is converted and killed.
Twelve year old Jacky (it is unknown whether this was her real name or an alias) ran away from her home on Taurus 1, stowing away on the New Oslo Shipping Corporation transport Hunter Gratzner. When the ship crashed on M6-117 the survivors found her in the wreckage. Saying her name is Jack & pretending to be a 12 year old boy because she feels she would be taken more seriously & "hassled less", she grows close to a few survivors, including the bushwhacker Shazza, a young Muslim teen named Ali, and the the ship's first officer Carolyn Fry. She also established herself as an antagonist of Paris P. Ogilvie, an antiques dealer.
After Zeke was killed, Fry and the others assumed that Riddick killed him. Riddick was caught soon after and secured in one of the ship's holds. While Fry was trying to interrogate Riddick, Jack sneaks in and asks him how he got his eyes. Riddick tells the steps, beginning with murder, something she says she's willing to do.
Fry's conversation with Riddick compels Fry to seek evidence about the truth of his death. As she searched an underground cave for Zeke's remains she discovered that it was not Riddick who killed him, but creatures indigenous to the planet. As the creatures closed in around Fry, Jack heard her and rallied the rest of the survivors to save her.
After it was established that Riddick didn't kill Zeke & with the stress of deadly predators added to the trauma of the crash, along with whatever drove her from her home on Taurus 1, Jack quickly became obsessed with Riddick's strength & survival instincts. Jack adopted several of Riddick's traits, shaving her head, wearing old broken goggles, and using profanity to mimic her new hero. Riddick soon realizes that Jack is actually a female and she has begun her menstrual cycle, giving the bioraptors a blood scent by which to track them. 
When they finally get to the escape ship the only survivors are Riddick, Abu al-Walid, and Jack. As they are leaving the planet, Jack asks what they should say if they run into bounty hunters or other law enforcers asking where to find Riddick. Riddick responds: "Tell 'em Riddick's dead. He died somewhere on that planet."
Captured on The Kublai Khan
Shortly after escaping the planet, Riddick, Jack, and Abu al-Walid are picked up by the mercenary ship Kublai Khan, captained by Antonia Chillingsworth, a collector of criminals, whom she freezes and keeps as "art" statues. Although the criminals are frozen, they are still alive and conscious. To her Riddick is the ultimate "masterpiece" for her collection. Riddick, Jack, and Abu al-Walid must fight their way through an army of mercs and creatures at her disposal.
Jack discovers her violent side by shooting Antonia Chillingsworth just before she can kill Riddick. This discovery is clearly a source of worry for Riddick and Abu al-Walid as the three escape from the mercenary ship. This manifests itself in Riddick's decision to deliver both Jack and Abu al-Walid to New Mecca.
The Lost Years
Five years pass between Jack's arrival at New Mecca and her Incarceration at Crematoria. It is during this time that a seventeen year old Jack takes on the name "Kyra". Whether this is her real name or a nom de guerre is a mystery. When they're reunited on Crematoria she tells Riddick briefly about what has happened to her during the five years since they last spoke. She mentions that she joined the mercenaries on the planet Lupus 5, which appears to be barren and over-industrialized and contains a well-developed space transportation industry. It is possibly a merc recruiting hotspot.
Kyra eventually became a criminal, convicted of 4 counts of manslaughter and 3 first degree murders. Her first kill was Antonia Chillingsworth, commander of the merc vessel Kublai Khan. Further kills include a brethren of Rykengolls after she was enslaved and brutalized by them. She had a 700,000 UD bounty and was caught after leaving the Helion System for the Proxima System. She was held in the Crematoria Slam Facility.
From Crematoria to the Underverse
After Riddick runs into Toombs again On New Mecca. Riddick allows himself to be captured so he can be transported to Crematoria, a prison on a dead world where daytime surface temperatures scorch the face of the planet. Here Riddick is reunited with Jack, and learns she now goes by the name of Kyra. She blames him for leaving her and Abu al-Walid in New Mecca.
When they first meet again they have a nostalgic conversation. Riddick quickly learns that Kyra is a very different person from the "Jack" he knew five years ago; an emotionally detached survivor in peak physical condition with keen senses, and experienced in martial arts. Kyra appears to still be obsessed with becoming like Riddick. The tough ex-merc occasionally discloses an occasional aching vulnerability; she appears to be in love with Riddick in some twisted way. In the prison hierarchy, Kyra appears to be extremely independent.
She was always on the move and liked to hide around the prison in small areas that are difficult for others to reach. She doesn't talk with anyone unless she has to. She is known by the guards as always having a shiv on her somewhere. She likes to hide a razor in her mouth which she uses to cut Riddick on his left cheek (dubbed, the Kyra Kiss). Her favorite game is "Who's the better killer".
When an opportunity for Riddick, Kyra, and some of the inmates presents itself for an escape they decide to try and reach a hanger with a ship by traveling on the surface, surviving by keeping pace with the temperate zone created between the scorching heat and freezing cold of Crematoria's daily cycles. They reach the hangar, but Vaako and his soldiers have arrived on the planet.
Riddick and Kyra are forced to fight the Necromongers. Vaako and the surviving Necromongers make their escape, taking Kyra with them. She believes Riddick has perished on the surface of Crematoria.
After Riddick is saved by the Purifier, he flies Toombs's ship back to Helion Prime, intending to rescue Kyra. Riddick makes his way to the throne room on the Basilica, where he comes face to face with the Lord Marshal, who reveals Kyra has converted to their faith. She wears a new recruit gown and has the two "pain" marks on each side of her neck and appears pale and zombie like and has eyeshine in her eyes. Riddick does battle with the Lord Marshal, whose unique powers prove too great for Riddick to handle.
Before the Lord Marshal can deliver the final blow, Kyra stabs him in the back with a spear; she is apparently coherent enough to realize Riddick is in great danger. When she saves Riddick, her eyes return to their normal state. The Lord Marshall then backhands her, she goes flying into a spiked column, mortally wounding her. After Riddick kills The Lord Marshall he turns to the mortally wounded Kyra. She dies in his arms. Her death reduces Riddick, who very rarely shows any emotion besides contempt, to tears.
Appearance and Personality
When Kyra went under the alias "Jack", she was originally thought to be a twelve year old boy. She had dark brown hair and bright blue eyes. In Pitch Black, she had cropped cut hair, a slightly deeper voice, and wore male clothing to add to this ruse. Because she used to be teased, she thought that being a boy was easier than being herself due to being a tomboy. As a way of looking up to her new idol, Riddick, she later shaves her head bald and begins to use more profanity to mimic the convict. She even occasionally wears a set of goggles she found. When her deception is discovered, she stops pitching her voice lower.
Five years later a seventeen year old Jack goes by a new name, "Kyra". She now has much longer brown hair had matured into a beautiful, athletic woman. Because of the five years she spent with mercenaries, she has grown colder; vindictive and calculating. At times she displays moments of vulnerability, usually when she's around Riddick. She still seems to be obsessed with Riddick and to warped degree appears to harbor romantic feelings for him.
There were rumors of a television movie and possible series to be produced on the Sci-Fi Channel shortly after The Chronicles of Riddick was released. Kyra would have been the main character and the series presumably would have covered the events during the five years between Pitch Black and The Chronicles of Riddick.