Jeff used to work in I.T and developed a music software that was supposed to belong to Carrington Atlantic, but a judge disagreed and Jeff went on to earn his first billion dollars, which made him Blake Carrington's number one enemy, who admits to hating him on multiple occasions.
In "I Hardly Recognized You", after Blake refuses to give Fallon Carrington a job of importance in his company, she teams up with Jeff, and he offers her financial backing to be the chief executive officer of Carrington Windbriar, her own company that she's starting, which will also be Blake's new competition.
In "I Answer to No Man," when Fallon gets kidnapped by Alejandro. Knowing that Michael was sent by Blake to watch Jeff, they both start to fight and after they fight the two work together. It could be the fact that Michael asks Jeff for help to save Fallon.
He has a father who was arrested on alleged drug charges and sent to prison after Jeff's mother was having an affair with Blake Carrington, and Blake wanted Jeff's father out of the picture. When Jeff found out about it, he started a plan to get close to the Carrington's to get revenge.
In Trashy Little Tramp and Dead Scratch, it is revealed that Jeff and Monica Colby are half-cousins to Fallon Carrington as Thomas Carrington, Fallon's grandfather, had an affair with Jeff's grandmother.
In "Mother? I'm at La Mirage", Jeff received treatment for his neuro-toxin condition that had appeared as a result of Adam's poisoning. Because of the illness, Jeff will slowly lose his ability to speak, basic motor skills, and functions. The effects could become apparent in years or months.
- Main article: Fallon-Jeff relationship
As children, Jeff had a crush on Fallon but their relationship was ruined by Blake, who didn't want them to date. As adults, their relationship was strictly business before it turned romantic. Jeff's intentions with Fallon became hazy after he confessed to his father in Rotten Things that he is using Fallon to get revenge on Blake. They later made amends after they learned they were cousins. When Jeff went missing Fallon was one of the first people to look for him. Now that Jeff is married to Fallon's mother, Alexis Carrington, Fallon is technically Jeff's stepdaughter.
Alexis Carrington Colby
Alexis and Jeff have a complicated history. When Jeff was a teenager, he had a crush on Alexis's daughter, Fallon. He wanted to take her to a school dance which Alexis thought was sweet. However, Blake refused to allow their relationship to blossom and blackmailed Jeff into standing Fallon up. When Jeff tried to go through with his plan, Alexis intercepted Jeff and lied about Fallon leaving with someone else. She always tried to protect the boy. Years later, Alexis returned to Atlanta now married to Jeff. While to the public eye they are an unexpected yet in-love couple, their entire marriage is merely a business deal. They are helping each other get revenge on Blake. Despite this, Alexis cares for Jeff and has eluded to wanting more out of their marriage.
|Dynasty: Season 1 (20/22)|
|"I Hardly Recognized You":||"Spit It Out":||"Guilt is for Insecure People":||"Private as a Circus":||"Company Slut":||"I Exist Only For Me":||"A Taste of Your Own Medicine":||"The Best Things In Life":||"Rotten Things":||"A Well-Dressed Tarantula":||"I Answer to No Man":|
|"Promises You Can't Keep":||"Nothing But Trouble":||"The Gospel According to Blake Carrington":||"Our Turn Now":||"Poor Little Rich Girl":||"Enter Alexis":||"Don't Con a Con Artist":||"Use or Be Used":||"A Line From the Past":||"Trashy Little Tramp":||"Dead Scratch":|
|Appears||Appears||Appears||Appears||Appears||Credit Only||Credit Only||Appears||Appears||Appears||Appears|
|Dynasty: Season 2 (17/22)|
|"Twenty-Three Skidoo":||"Ship of Vipers":||"The Butler Did It":||"Snowflakes in Hell":||"Queen of Cups":||"That Witch":||"A Temporary Infestation":||"A Real Instinct for the Jugular":||"Crazy Lady":||"A Champagne Mood":||"The Sight of You":|
|Appears||Appears||Appears||Appears||Appears||Credit Only||Appears||Credit Only||Appears||Appears||Appears|
|"Filthy Games":||"Even Worms Can Procreate":||"Parisian Legend Has It...:||"Motherly Overprotectiveness":||"Miserably Ungrateful Men":||"How Two-Faced Can You Get":||"Life is A Masquerade Party":||"This Illness of Mine":||"New Lady in Town":||"Thicker Than Money":||"Deception, Jealousy, and Lies":|
|Credit Only||Credit Only||Credit Only||Appears||Appears||Appears||Appears||Appears||Appears||Appears||Appears|
|Dynasty: Season 3 (15/20)|
|"Guilt Trip to Alaska":||"Caution Never Won A War":||"Wild Ghost Chase":||"Something Desperate":||"Mother? I’m At La Mirage":||"A Used Up Memory":||"Shoot From the Hip":||"The Sensational Blake Carrington Trial":||"The Caviar, I Trust, Is Not Burned":||"What Sorrows Are You Drowning?":|
|"A Wound That May Never Heal":||"Battle Lines":||"You See Most Things in Terms of Black & White":||"That Wicked Stepmother":||"Up A Tree":||"Is The Next Surgery on The House?":||"She Cancelled...":||"You Make Being a Priest Sound Like Something Bad":||"Robin Hood Rescues":||"My Hangover's Arrived":|
- In the original series, Jeff and Fallon develop a strong relationship very quickly and are soon married. Jeff also had a kind relationship with Blake, who thought of him as a son.
- The "new" Jeff is morphed with the original Cecil Colby, who was his uncle and a strong rival to Blake. In the reboot, Cecil Colby is Jeff's father and not his uncle. Jeff follows his father's footsteps to get revenge.
- This Jeff Colby is shown to be bilingual, speaking excellent Yoruba and English while his original counterpart didn't know Yoruba because he wasn't of Nigerian descent.