Following the harrowing events of Season 3, the Titans are on the road back to San Francisco when Bruce calls Dick with a special offer for Conner—the chance to meet Superman himself. The team takes a quick detour to Metropolis to check out the S.T.A.R. Labs facility, where the Man of Steel is unfortunately unable to meet his young charge due to an emergency in outer space. However, Conner's other father, Lex Luthor, has taken an interest in meeting his "son", leaving the Titans scared at what he has planned for their friend. Meanwhile, across the city, grisly murders are being committed in cold blood, and Raven is getting a horrific taste of things to come.
"Lex Luthor" contains the following tropes:
- Ambiguous Innocence: Much of Luthor's discussion with Conner is regarding how he wants his "son" to become the hero his father never could be, and even be a better man, but given Luthor's history both in Titans and through his numerous counterparts in the DC Multiverse being known liars and manipulators, it's very hard to say if he's being honest or if he's just telling Conner what he wants to hear.
- Bald of Evil: As is tradition with Lex, he's described as Superman's Arch-Enemy and has no hair on his head to speak of.
- Bait-and-Switch: At S.T.A.R., Dick reveals he has a surprise for Tim. Tim thinks it's the Robin suit, but Dick reveals that he's not going to give it to him just yet considering he only started being a Titan a few days ago. What he has made for Tim is a bo-staff to train him.
- Character Death: Luthor dies from coughing up a large chunk of blood and simultaneously choking on a giant snake that somehow spawned inside his body.
- The Chessmaster: Luthor deduces that the other Titans won't let him see Conner without figuring out what's happening first, so he lets Kori storm into his building while Dick and Tim try to hack him while he's distracted. The Titans do hack his computer, but he makes it clear he knows he's on to them, and sends ninjas to attack the two as a warning not to prevent Conner from meeting him.
- Clark Kenting: Homaged when Conner is given a pair of glasses to wear that make him look like Clark, which Dick subtly chuckles at.
- Death by Secret Identity: Subverted in that Luthor seems to have known Superman's real name for some time, and we don't know if he ever took advantage of that. However, this is his first appearance on this show, and he doesn't survive.
- Dissonant Serenity: While Starfire is beating the crap out of Luthor's guards, Lex just casually strolls past his dinner table to get more wine, although it turns out to be Justified when it's revealed he knew Dick and Kori were trying to spy on him.
- The Dreaded: Once Luthor enters the plot and wants to see Conner, Dick and Kori both try to warn their friend not to go meet with him given how villainous he's been over the past 40 years. When Conner, Rachel, and Garfield stop by The Daily Planet to check on Luthor's files in the archives, the archivist outright states they have far too many files on the man, including space crimes, fake trials, and even piracy.
- Frame-Up: When Luthor dies, the guards arrive to find Conner over their boss's limp body, his hands covered in blood, when a snake that somehow spawned in his body was the culprit.
- Freak Out: As a result of Rachel's literally bloody visions, she winds up scared beyond belief when she can't make sense of it.
- I Have No Son!: Inverted. Conner outright tells Lex he doesn't consider him to be his father.
- I Warned You: Mother Mayhem warns Lex that for the power he seeks to avoid dying, someone will pay the price, which Lex dismisses as that always being the case. When he does die, she's seen outside his tower repeating her warning.
- Honor Before Reason: Conner is well aware that Lex is a terrible person, and both Dick and Kori warn him that Lex is trying to play him for something given that he's dying and has been looking into new blood transfusion methods to stave off his demise. Still, Conner chooses to do the right thing and at least hear his father out.
- Immediate Sequel: The season picks up a few days after the end of Season 3.
- Laser-Guided Karma: The moment Lex gets access to the monument, he kicks the future Mother Mayhem off the project. She warns him that for the power he wants, someone will pay the price. At the end of the episode, Luthor winds up paying that price by choking on both his own blood and a giant snake.
- Leaning on the Fourth Wall: Two characters randomly appear commenting on a show about they're not focusing on the main cast and just introducing random new characters—which is what the show is doing at that very moment.
- Missing Time:
- A brief example. When Gar uses his new suit, he's about to transform when his mind suddenly enters into a mysterious place with a giant tree. Only a few seconds later, the entire lab is trashed, with Gar having no memory of what happened. Dick and Connor have to tell him that he turned into a gorilla, then a velociraptor, then an armadillo during his rampage.
- Likewise, when Rachel has her visions, she can't remember even having them.
- Mundane Utility: Gar uses his shapeshifting skills to change his arm into a squid's tentacle during a bowling game, landing him a strike. Rachel tries to call him out on cheating with his powers.
- Mythology Gag:
- Tim gets his trademark bo-staff in this episode.
- Luthor dying of Kryptonite poisoning was a major subplot in The Death of Superman and the subject of a Myth Arc on Justice League as a follow-up from Superman: The Animated Series.
- No Good Deed Goes Unpunished: Conner decides to do the right thing and hear Lex out, even agreeing to stay with him for a little while. Instead, Lex winds up choking on a snake and coughing up an exuberant amount of blood before dying, leaving Conner over his father's body while it appears he killed him.
- The Reveal: Luthor is dying of Kryptonite poisoning he contracted two years prior, and he wants Conner to succeed his legacy.
- Rule of Symbolism: Blood. It appears in several of Raven's visions in place of ordinary objects, the murder victim winds up eating some before she's killed without knowing it, Luthor coughs up blood before he chokes on a giant snake, and the episode introduces the character of Sebastian Blood, who's taxidermies start spewing the stuff out before he experiences a similar coughing fit of blood.
- Sacrificial Lamb: The blue-haired girl introduced in this episode is killed by the mysterious masked murderer only a minute after appearing, her throat getting slit in the process.
- Secret Secret-Keeper: Lex is aware that Clark is Superman in this continuity, as he speaks with a bit of disdain when he hears Conner chose Clark's name.
- So Proud of You: Although Superman isn't able to meet Conner due to an emergency, he writes a letter expressing his pride in his "son" and how much he wants to meet him.
- Surprisingly Realistic Outcome:
- Tim thinks that Dick is prepared to give him a Robin suit at S.T.A.R., but Dick states he's not ready for it yet since he only just became a Titan a few days ago.
- Tim only just got a bo-staff from S.T.A.R. and hasn't been trained to fight with it yet, so Dick has him stay back when they're ambushed by ninjas. When Tim is forced to defend himself, he's only able to block before Dick has to swoop in and save him.
- We Hardly Knew Ye: Luthor's sole appearance thus far in this series ends with him chocking on a snake and dying in his son's presence.
- Wicked Cultured: Although Luthor is still a bad guy as far as the other Titans are concerned, he lives in a very posh tower, eats fancy dinners, and even purchased a very expensive set of wine at auction. He even goes so far as to show a prominent painting to Kori when she barges into his office.
