Batman or Batgirl comes to Jump City from Gotham in order to entrust Robin with task or request something from him. This usually has side effect of the Titans finding themselves dealing with a member or two of the Dark Knight's rogues gallery.
Justice League members make an appearance, with these tending to be the DC Animated Universe versions.
Robin revealing his Secret Identity and/or talking about his past to his friends, or just one other character if it's a shipping fic (usually Starfire or Raven).
This often goes hand-in-hand with fanfics that depict the briefcase from "Revved Up" containing something connected to Robin's childhood circus days, like his "Flying Grayson" uniform or a picture of him and his parents.
The return of Beast Boy's, well, Beast Form from "The Beast Within". Due to said episode showing how the Beast instinctively protected Raven, most of these fics involve the BBRae pairing as a major aspect of the story, with the Beast being used as a literal or thematic parallel to Raven's demon side.
Raven has one of her long-lost demonic siblings appear, be it one of her actual half-brothers from the comics or some OC.
There are a multitude of fanfics where Raven tries to kill herself, or at least thinks of it, in order to stop Trigon from using her as a portal. Rarely does she succeed though.
Any and all variations of the High School AU, ranging from the group being normal civilians, to having secret identities, to simply attending school during lulls in crime.
Slade has a new apprentice, often in the form of an original character.
AUs where Robin has been Slade's apprentice for longer than in canon are common.
Jericho being revealed as Slade's child to the team.
The team meeting Rose Wilson, who oftentimes wants revenge for Slade's death. Whether or not these stories end with the same Heel–Face Turn seen in the comics, with Rose joining the Titans or at least becoming amicable with them, varies.
Even fanfics that only have him show up as a supporting character will generally have the identity of Red X revealed at some point in the narrative to be Jason Todd, the second Robin.
Cheshire and Speedy falling for each other, due to them being an on-and-off couple in the comics.
Working off the Go comic mentioning Starfire having a missing younger brother named Wildfire, some fan works try to reunite the two siblings.
Some fanfics will expand or retcon the show's character backstories to make them closer to their original comic book origins, with Beast Boy and Starfire being the most common ones given this treatment.
Speedy as either a recovering drug addict or as hiding a drug addiction.
Future fics where Nightwing and Starfire raise their daughter Mar'i Grayson together. Fics written after 2017 tend to include Jake Grayson as Mar'i's younger brother.
A Flash Forward Fic that follows the next generation of Teen Titans, made up of the main characters' children. This can also include Kid from the Future fics where a time-travel related mission their team was on caused them to travel back in time, and they must work with the present-day Titans to return home.
Prior to the final episode, fanfics where Terra came back from the dead (often wrong) were incredibly common. Following its airing, wherein Terra did come back from the dead, these branched off into stories where (depending on how you interpreted her actions during the episode) Terra gets back her memories or admits to faking her memory loss in order to enjoy a normal life. Both of these situations feature Beast Boy trying to convince her to return to the Titans; if he isn't successful by the end, he either eventually learns to accept her decision or continues to angst about the situation, though Fix Fics where Beast Boy and Terra end up getting their happily ever after were relatively common. More rarely, the girl turns out to not actually be Terra, leading to a mystery plot where the Titans search for the location of the real Terra.]
Jinx having a Dark and Troubled Past involving Fantastic Racism for her skin and powers. Oftentimes she's also an immigrant from India, which references the character she's based off of.
Teen Titans fanfics mostly based on the show, will borrow from the comics and Justice League cartoon. Probably the most explicit form of this is the Fandom-Specific Plot of Batman coming to Jump/Robin going back to Gotham, Starfire and often Beast Boy sharing backstories more closely tied with their comic selves, or the main characters being referred to by their real names.
Nightstar, Robin/Nightwing and Starfire's daughter from Kingdom Come, is quite popular and is the subject of many fan fics, even though a large fraction of fans (given much of the show's fanbase is younger people who don't follow the comics) seem to have never read the source material or just skimmed it for Nightstar and Robin/Starfire content. Similarly, there's the newer Jake Grayson, their son from Nightwing: The New Order, who is also lumped in with the family.
