Among Batman's most reliable allies in Christopher Nolan's The Dark Knight trilogy is the Wayne Enterprises employee, Lucius Fox (Morgan Freeman). While Bruce builds most of his Batman gadgets and vehicles by himself in many adaptations, it's Fox that does most of the work for him in the trilogy.
Freeman's version of Lucius Fox is undoubtedly the best to ever appear in a live-action project, but the character doesn't just stand out because of the actor's star power. Lucius is humorous, intelligent, and principled. His banter with Bruce is always something to look forward to and as such, he has many great remarks.
When He Disagrees With Bruce's Decision To Monitor All Gotham Cellphones:
"Spying On 30 Million People Isn't Part Of My Job Description."
One of the reasons the Joker is the most formidable among the best Dark Knight trilogy villains is that he is slippery. To make it easier to track him, Bruce builds a surveillance system that can help him listen to every phone conversation in Gotham. And to ensure it isn't misused, he entrusts Lucius with handling. However, the elderly techie doesn't think it's such a good idea.
Throughout the trilogy, Lucius is depicted as a conscientious individual. He, therefore, sees Bruce's plan to spy on people as a bit extreme. However, Bruce is right that many lives will be lost if the Joker isn't stopped. Since the Clown Prince of Crime isn't playing fair, it's only right that he briefly switches off his conscience too.
When He Praises Bruce After Catwoman Saves His Life:
"I Like Your New Girlfriend."
A handcuffed Lucius is saved by Catwoman when thugs allied to Bane hold him captive. Impressed, he tells Bruce that he approves of his new girlfriend.
In Catwoman, Batman not only has a lively romantic partner but also a strong ally. Although Bruce doesn't like the fact that she is a thief, she definitely causes less harm and more good. In another scene, Alfred also approves the relationship, further convincing Batman that Catwoman is indeed right for him.
When Bruce Doesn't Ask Him For A Favor:
"These Conversations Used To End With An Unusual Request.”
After defeating the Joker, Bruce vows to retire. During his next conversation with Lucius at the Applied Science Division, he only talks about business options for Wayne Enterprises (which surprises the Batman associate).
That Lucius expects Bruce to always make a vigilante-related request isn't surprising since that's all he does in the first two movies. Hearing Bruce ask about business feels odd to not only Lucius, but also the audience. However, Batman genuinely believes that he has nothing more to do after defeating the Joker. This is soon proven wrong.
When Bruce Asks Him How He Can Get Lau Inside A Plane:
"I'd Recommend A Good Travel Agent."
Seeking to capture Lau, the CEO of Lau Security Investments Holdings, and bring him back to Gotham, Bruce asks Lucius how he'll be able to get him into the plane quickly. As expected, Lucius has the appropriate cheeky answer.
Lucius makes a habit of joking when Bruce asks serious questions. The mission to extract Lau from Hong Kong is an important one as it would require doing so hastily with a plane. Still, it's funny hearing Lucius suggesting that a travel agent would do a better job at getting the mob associate inside a plane to Gotham.
When He Explains To Earle What He's Still Doing At Wayne Enterprises, Despite Getting Fired:
"I Got Another Job: Yours."
When a Wayne Enterprises microwave emitter goes missing, William Earle, one of the least featured characters in the Dark Knight trilogy, fires Lucius Fox for asking about ut. But when Bruce Wayne buys the majority of the shares, he replaces Earle as CEO with Lucius. When Earle heads to the boardroom, he is shocked to fund Lucius in charge.
It's a joyous moment when Lucius takes over Earle's job because the CEO was taking the company in a direction that Thomas Wayne never intended. Since Earle hates Bruce Wayne, audiences have no choice but to root for his downfall. And the feeling is even better than that happens because it's a fan-favorite character that takes his place.
When He Makes Fun Of Bruce's Request For A New Bat Suit:
"Yeah, 3 Buttons Is A Little '90s, Mr. Wayne."
Not convinced with the functionality of the old bat suit, Bruce visits Lucius so that he can design a new one for him. Although Lucius understands what he means, he jokes about his current three-button business suit, claiming its old fashioned.
Lucius never misses the opportunity to make a joke and he does so again here in a brilliant manner. Since he is not a tailor, he definitely knows the kind of suit Bruce is asking about but he goes on to poke fun at his business attire anyway. Looking fashionable has never been one of Bruce's priorities either.
When Bruce Is About To Say 'Bat':
"Like A Submarine, Mr. Wayne. Like A Submarine."
As Bruce and Lucius are examining a sonar phone at a midlevel shopping center in Hong Kong, Lucius explains how it emits high-frequency pulses. Just as Bruce is about to say "Just like a Bat," Lucius cuts in.
All of Bruce's friends know about his obsession with bats, but it gets annoying for them when the billionaire tries to compare everything with the winged mammals. Lucius' words are meant for humor purposes, but they also serve as a reminder to Bruce that bats aren't the only things associated with high-frequency pulses.
When He States The Name of The New Batwing:
"It Has A Long Uninteresting Wayne Enterprises Designation. I Just Took To Calling It The Bat."
Shortly after retiring, Bruce considers going back in when he sees the new Batwing Lucius has gotten for him. He asks what its name is and Lucius summarizes it.
Lucius always makes sure to not bother Bruce with machine and computer jargon. By simply naming the new aircraft, The Bat, he makes things easier for everyone. The Bat is one of the best versions of the Batwing and the name is fitting too since the aircraft has Bat-like features and more. Most importantly, it's such a good-looking jet that it motivates Bruce to wear the Bat-suit again.
When He Reacts To Bruce Mishandling The New Batsuit:
"Perhaps You Should Read The Instructions First?"
As he is examining the new Batsuit, Bruce presses a button that causes spikes to fly off. One of them almost hits Lucius, which is why he advises Bruce to read the manual first.
Bruce sure does behave like a kid with a new toy when he sees the Batsuit. He figures that since he is Batman, operating it shouldn't be a challenge. However, what he isn't aware of is that Lucius has made several modifications. The new features include a separable cowl, sonar vision, and gauntlet fin projectiles
When He Is Suprised At Bruce's Reappearance:
"What Brings You Out Of Cryo-Sleep Mr. Wayne?"
Having not seeing him in a long time, Lucius is surprised when Bruce comes to visit him again. He thus jokes that the Gotham billionaire has finally decided to come out of his cryo-chamber.
To Lucius, Bruce's time away felt like cyro-sleep since he never bothered to communicate. With the quote, Lucius also paints himself as the go-t0 guy in case Batman needs anything. Over the course of the trilogy, he appears to rely on him even more than Alfred. As such, this version of Lucius Fox can be considered the most competent one in DC history.
