Cecil Colby is Blake Carrington's alleged friend, up to the point when oil businesses gets in the way, a shrewd businessman who built the "ColbyCo. Oil" company by his own ability hoping his nephew Jeff will make himself responsible for it one day.

As a result of his unusual and raw approach to business deals and other professional arrangements that he was mixed up in. Cecil was an object of suspicion and vengeance, a person who's beyond the pale and who's fit for charity as much as any common thief. Even though he practically raised Jeff, being his only father since his brother Philip vanished without a trace during the Vietnam War, Jeff was never the very image of his uncle. On the contrary, Cecil failed to re-educate him.

Knowing that Blake was in financial trouble, Cecil decides to help him by asking his daughter Fallon to marry Jeff and to make everyone happy, but, owing to Blake's limo-driver Michael Culhane, his plans are disclosed and Blake starts losing confidence in him. Slowly but undoubtedly, Blake and Cecil are becoming opponents, especially after Blake is cut off permanently from their mutual "off-shore" deal and told to pay off a loan. Disliking Blake very strongly because of his business accomplishments and the happiness of the Carrington family, Cecil starts considering all possibilities how to defeat him, and humiliate him as well, so he takes advantage of mentally unstable Claudia Blaisdel and suggests her to use either Blake or Jeff, or both of them if it's necessary, so that she could inform him of "Denver-Carrington" oil-shale extraction process.

Exposed as an imposter, sophisticated idler and, above all, wretch - even suspected of being Fallon's father which happens to be only Alexis Carrington's pathetic lie - Cecil makes use of his last trump card and even poses as the mobster by the name of Logan Rhinewood who's behind the attack on Blake. He manages to catch not only a one part of Blake's football team, but also a solid pile of "Denver-Carrington" shares, yet, the last thing he managed to catch is a massive heart attack that brings him to the hospital.

Just a few minutes before his death, he's wed to Alexis and signs over the company to her name wanting her to destroy Blake, or better yet, to destroy each other some day in the future.