WARNING: The following article contains spoilers for the Titans Season 1 episode "Donna Troy," streaming now on DC Universe.

Nods to the Batman mythos have been sprinkled throughout Titans since the premiere of the live-action series, with flashbacks to the Batcave and Wayne Manor (complete with shadowy cameos by Bruce Wayne), a prominent guest appearance by the second Robin, Jason Todd, and a phone call to Alfred Pennyworth. However, the most common shoutouts have been to the Dark Knight's foes.

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The Joker was mentioned in the first episode by Detroit police officers concerned that the sudden reappearance of Robin could attract crazies from Gotham, while the deeper exploration of Dick Grayson's backstory brought with it a mention of Two-Face, and roles, in flashback, for mobster Tony Zucco and the Maroni crime family. This week's episode, "Donna Troy," continues the trend with not only a mention of another of Batman's rogues, but also an elaboration of the threat posed by this version of the Clown Prince of Crime.

The Penguin

Deciding to walk away from his Robin identity, Dick Grayson (Brenton Thwaites) seeks out his longtime friend Donna Troy (Conor Leslie), the former Wonder Girl. Rescued as a young orphan by Wonder Woman, and raised on Themyscira, she's well-adjusted and far better equipped than Dick to navigate life outside a brightly colored costume. Forcing Dick to accompany her to a gallery showing of her photographs, Donna places the one-time Boy Wonder in a situation for worse than anything Gotham's villains could concoct: He must try to socialize with strangers, on his own. "I wonder what The Penguin's doing right now?" he wonders to himself.

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It's a funny, throwaway line that underscores that he rather be most anywhere else than where he is, left to his own devices in an art gallery. But it also provides that much more evidence that, aside from a Batman who apparently relishes killing, the world of Titans is very much like the DC Universe we know, right down to Gotham's colorful supervillains.

Young Donna Troy and Dick Grayson on Titans

More interesting, however, is the episode's opening flashback, which sheds light not only on the older sister/younger brother relationship between Donna and Dick, but also the unsettling nature of this incarnation of The Joker (who's, of course, mentioned but not seen).

In the scene, a young, and clearly upset, Dick returns to find a teenage Donna camped out on his bed. Despite Bruce's warning, Robin accompanied his mentor to an encounter with his archenemy, and now wishes he hadn't. "A lot of people died," he tells Wonder Girl. "We couldn't save them."

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Choking back tears, Dick tells Donna that he feels like quitting. But Donna, whom we're reminded is older, smarter and prettier than Dick, pulls out the reverse psychology, asking whether he thinks The Joker will quit, too. "No," Robin replies. "Bruce says The Joker killer people just because he can. He's never gonna stop."

It turns out that, in this universe too, some people just want to watch the world burn.

Now streaming on DC Universe, Titans stars Brenton Thwaites as Robin, Anna Diop as Starfire, Teagan Croft as Raven and Ryan Potter as Beast Boy, and guest starring Conor Leslie as Donna Troy.