Paul Lewiston, portrayed by Rene Auberjonois, is the "lawyer's lawyer", watching out for the firms business and reputation. He has a long-standing friendship with all three Partners, but, at times, his loyalty to Denny Crane is tested when Denny's actions run contrary to the best interests of the firm.

Paul's wife Olivia passed away from cancer. His relationship with his daughter, Rachel Lewiston, was strained by his 'by the book' parenting and, finally, the two became estranged when Rachel escaped into the world of a meth addict. She disappeared for seven years and gave birth to a daughter of her own, Fiona, now three, making Paul a grandfather, unbeknowst to him. In "Live Big", Paul explains to Shirley Schmidt where things went wrong:

Paul: "I did her homework with her, I drove her to the prom, all the nights I waited up."
Shirley Schmidt: "What happened?"
Paul: "She basically stole from me. You name it. She’d feign problems with rent. Her health. Credit card debt. She’d invent all kinds of crisis to impel me to write a check, the proceeds of which would always go to feed her drug habit. The last straw, I got her in a program, an exclusive one, I told her if she left she was cut off. We had a fight. I haven’t spoken to her since. That was seven years ago."

Paul sought out Rachel and attempted to reconcile, but there were resentments on both sides, both feeling a need of an apology. In a dramatic confrontation, Rachel told her father why she resented him:

"Rachel Lewiston: Well you know what, dad? In my darkest day… through it all… I had one little thing, one tiny semblance of a foundation. And it was knowing that no matter what, my father would be there for me. And he wasn’t. He wasn’t. How dare you take that from me?"

In "Shock and Oww!", Paul and Rachel reconcile, but he remains skeptical as to her sobriety, sending Brad Chase undercover to ascertain is she was still using meth. She was.

In "Stick It", Paul forced her to check in to rehab and assumed temporary custody of Fiona. In "Chitty Chitty Bang Bang", Paul considers a new path, telling Shirley and Denny, "It’s that my priorities are different now and suddenly this firm doesn’t seem so important." He even hypothetically asks Denise if she would consider starting a practice with him.

Denny, who thinks he can run the firm without Paul, gives in to Shirley's more realistic assessment and gives Paul a symbolic sheet of paper, blank except for the letterhead which reads "Crane, Poole, Schmidt and Lewiston":

Paul Lewiston: I can’t accept this.
Denny Crane: I thought it was what you always wanted?
Paul Lewiston: I’m sure it’s what you thought I always I wanted.
Denny Crane: You trying to play hardball with me, Paul? Don’t tell me this whole thing is simply a matter of respect? (Paul gives him a look.) Good God, it is.
Paul Lewiston: My mind and my priorities are exactly where they should be right now. When Rachel gets out I will be back here full time. Or maybe I won’t. In the meantime it will give you the opportunity to actually think about things for a change.

Paul and a now-clean Rachel reconcile in "Squid Pro Quo", building a comfortable relationship centered around their love for Fiona.