DC Universe's Titans landed with an impressive first season, with season 2 of the show confirmed before the first season even finished. The second season is currently on track to hit the streaming service in the fall of this year, and tons of casting news has been hitting the internet for months.
There's a lot of great material in the Teen Titans comic books that the show is probably going to pull a bit from, and with some of the casting news already announced, we can make some educated guesses as to what exactly to expect next season. Season 1 spoilers are going to abound here, and keep in mind some of these theories could turn out to be accurate, or the show could go in an entirely different direction.
SUPERBOY
The first new character that was teased for next season in a post-credits scene for the season 1 finale was Superboy (created by Karl Kessel and Tom Grummett). Joshua Orpin has been tasked with portraying the character on-screen.
There are a lot of different directions the show could go with this character, with a wide variety of interpretations in the comics. Generally, Superboy has "tactile telekinesis" abilities, which allow him to replicate many Kryptonian powers such as invulnerability, heat-vision, and flight, as well as move objects with his mind.
CONTROLLED BY CADMUS
In the comics and on a Prime-Earth storyline, Superboy is under control by an organization known as N.O.W.H.E.R.E. (who could easily be replaced by CADMUS who have already featured in the show) and tasked with taking out the Teen Titans.
In the post-credit scene of season 1, Superboy is shown escaping CADMUS, but who's to say they don't regain control of him at some point? Or haven't brain-washed him to attack the Titans on sight?
CONTROLLED BY LUTHOR
Superboy is a clone of Superman and a human, originally created from genetic material gathered from Superman after he was seemingly killed by Doomsday. The human donor in the comics (at one point, at least) was Lex Luthor.
Luthor implanted verbal commands during Superboy's time at CADMUS (much like Bucky Barnes was controlled in the MCU's Winter Soldier and Civil War) and used them to cause Superboy to lose control and attack the Titans, severely injuring all of them. Superboy eventually wrested free of Luthor's control, and stepped-down from being a superhero for a time.
DEATHSTROKE
Slade Wilson, also known as Deathstroke (created by Marv Wolfman and George Perez), likely needs very little introduction. Esai Morales has been cast as Deathstroke in Titans season 2, and a lot of fans are amped to see Deathstroke on-screen again. Deathstroke is heavily involved in a ton of the most iconic Teen Titans storylines, including The Judas Contract, which got its own animated movie adaptation in 2017.
He also has two children that are heavily involved in plenty of their own Teen Titans storyline, one of which is:
RAVAGER
Rose Wilson, the daughter of Slade Wilson and one version of Ravager (created by Marv Wolfman and Art Nichols) has also been cast in Titans season 2. Chelsea Zhang has been tasked with portraying Ravager on-screen. Ravager has been relatively consistent in the comics, ranging from anti-hero to vaguely begrudging hero.
Generally, Ravager was trained by any combination of her mother, Slade Wilson, and Nightwing. Ravager has low-level precognition, meaning she can sometimes see her opponent's next move, generally activating more consistently when she's got some adrenaline going.
TAKING DOWN SUPERBOY
Once again on Prime-Earth, this version of Ravager was employed by N.O.W.H.E.R.E. (who, again, could be replaced by CADMUS) and tasked with keeping watch over Superboy. It was Ravager's job to keep tabs on Superboy and take him down if he ever got out of control.
This led to Wilson actually being able to take down Superboy in combat although much of this would be due to her superpower of dampening other metahumans' powers.
TAKING DOWN THE TITANS
Ravager has also worked with her father from time to time, usually because Slade is manipulating her into doing so. At one point, Ravager and Deathstroke were fighting the Titans when Ravager hesitated to kill a member of the Titans.
Deathstroke plans to disown her, but to prove her loyalty to her father, Ravager gouged out her own eye to match him. Later on, Ravager breaks free of her father's influence, and even joins the Titans for a time.
JERICHO
Joseph Wilson, the hero who dons the name Jericho (created by Marv Wolfman and George Perez) and the son of Slade Wilson has also been cast in Titans season 2, portrayed by Chella Man. Jericho is (originally) a mute superhero, having had his throat partially slit before his father could rescue him.
Unlike his father and his sister, Jericho is a pretty kind-hearted and gentle person, who wanted nothing to do with the antics of his father. Jericho has the ability to possess others after making eye contact with them. If the person he possesses is unconscious, Jericho can speak through them, but otherwise communicates through sign language. While possessing someone, Jericho has access to their memories.
KILLED BY HIS FATHER
Throughout his time with the Titans, Jericho grew close to Raven, who appreciated him for his ability to listen and for his kind-hearted nature. At one point, Jericho tried to ease Raven's pain as Trigon's power grew inside her.
This resulted in Jericho being inhabited by the souls of Azarath, who had been tainted by Trigon, though neither Jericho or anybody else knew he had been inhabited at the time. Eventually, the souls of Azarath possessed Jericho, and he ended up attacking the Titans. In order to spare his son any further pain, Deathstroke seemingly killed Jericho himself.
THE JUDAS CONTRACT
One of, if not the most iconic Teen Titans storyline, The Judas Contract, was a four-part storyline written by Marv Wolfman and George Perez, with art by George Perez, Romeo Tanghal, Dick Giordano, Mike Decarlo, and Adrienne Roy, published in The New Teen Titans #42-#44, concluding in Tales Of The Teen Titans Annual. In Judas Contract, it's revealed that Deathstroke, who's been a near-constant antagonist for the Titans since the series began, has been working for the organization known as H.I.V.E.
The Titans had gained a new member in Terra who had been introduced quite a few issues earlier and gained the trust of the team, especially in Beast Boy. As it turns out, Terra had been giving Deathstroke information on the Titans the entire time, and Deathstroke finally springs his trap, managing to capture all of the Titans besides Dick Grayson and bring them to H.I.V.E. Together, Dick and Jericho manage to free the Titans, though Terra loses control and accidentally kills herself in the fight.