"Sidekick" is the pilot issue of Justice League/Teen Titans: Secret Legends.
- Terra / Tara Markov (Flashback and main story)
- Blue Lantern Corps
- Arisia Rrab
- Superman / Clark Kent / Kal-El (Flashback and main story)
- Geo-Force / Brion Markov (Flashback and main story)
- Supergirl / Kara Zor-El
- Hawkman / Katar Hol (First appearance)
- Captain Atom / Nathaniel "Nate" Adams (First appearance)
- Amelia Markov (Flashback and main story)
- Bolphunga the Unrelenting
- Vandal Savage (flashback only)
- Lex Luthor (flashback only)
- Slade (flashback only)
- Maxie Zeus
- Teen Titans
- Beast Boy (flashback only)
- Cyborg (flashback only)
- Raven (flashback only)
- Robin (flashback only)
- Starfire (flashback only)
- Ronnie Raymond (mentioned only)
- Viktor Markov (mentioned only)
Terra has completed the first phase of her training with Superman. But before setting out to her Tyrant Hunting campaign, she still had one more test to pass: to learn what it is like… to be a hero’s sidekick.
The story starts with a young woman pleading for her boss Maxie Zeus to spare the life of her boyfriend, whom Zeus threatens to kill for "trespassing his kingdom" until the couple is saved by Terra, who arrives there in time to defeat and restrain Zeus before carrying the couple safely to far away from the building, winning their gratitude before leaving. As she flies back home, Terra narrates her current experience, on which she crossed paths with many people after she was stripped off her memories while Vandal Savage took the life of her father along with numerous people in the congress by killing Ronnie Raymond.
She also remembers having met the Teen Titans before she forcibly left after crossing paths with Slade, who planned to use her as a living weapon against the young heroes. A plan which failed before it even begun when Superman arrived to restore her memories and reunited her with her brother Brion and their mother Amelia. Flashback ends with images of Tara's training with Superman and her acquisition of her JLA-made costume before Superman departed to space in the title of Grandmaster of the Blue Lantern Corps. In present day, Tara is practicing some more tricks with her powers before she is approached by Brion (in his mantle of Geo-Force) and Supergirl. The two notice she feels like she had not fully completed her training yet and Tara claims that, if she feels like Superman trained her like Batman trained the boys who took the moniker of Robin, then she has yet to know what it is like to be a hero's sidekick.
Terra is taken by the couple for a trip in an unknown planet where they could help her master this sense. By the time they arrive, they suddenly spot Hawkman and Captain Atom, who were assigned by unknown benefactors to protect an unknown artifact, battling a trio of alien mercenaries (consisting of Lobo, Reign and Bolphunga the Unrelenting) who were hired by Brainiac to retrieve that artifact. As Geo-Force and Supergirl join the battle, Terra is entrusted by Hawkman and Captain Atom to keep the artifact safe. She agrees, although she is annoyed by the two claiming that "this fight is not for sidekicks".
As she walks away from the fight, Tara slowly feels an unknown force coming from beneath the planet's underground as she is constantly told by a unknown voice to open the artifact. Unsure of what is going to happen, however, she is reluctant to do so. Just then, she is surrounded by Brainiac's spawns who demand her to surrender the artifact. She refuses and fights back. Suddenly, Terra's powers become greatly amplified in the fight. She initially believes she is losing control again until she senses life in the core of the planet. With no choice, she opens the artifact, which is revealed to be a Green Lantern power ring. The ring eventually crosses the ground and goes down bellow.
Terra suddenly realizes that she and the others are in Mogo, a living planet who was chosen to become a Green Lantern for his immense Willpower. Mogo awakens and disables the mercenaries. Brainiac attempts to obliterate him with his ship's Planet-Killing Weapon, but Mogo (with his powers combined with Terra's) fights back and destroys his ship, leaving Brainiac stranded and helplessly frozen in space.
The heroes are returned to Earth as Mogo voices his gratitude to Terra for bringing him back as Hawkman and Captain Atom apologize for doubting her. The group is approached by Superman and his fellow Blue Lanterns Mala, Arisia Rrab and Solovar as well as by Ganthet, who was the one who entrusted Hawkman and Captain Atom to protect Mogo's ring. Acknowledging what Terra has accomplished, Superman voices his approval, making Terra confident that she passed her test.
- (chapter opens with a young man laying down in the ground at the mercy of his unseen assaulter)
- Citizen: Please, don't do this! I just came to visit my girlfriend! I wasn't going anywhere private! I swear!
- (the aggressor is revealed to be Maxie Zeus)
- Maxie Zeus: Silence! First you tresspass the sacred land of Mount Olympus. Which is my kingdom! Then, you approach my muse without my permission. And now you say I know not what I think?! To the depths of Tartarus with you, mortal! (his Lightning Bolt rod ignites)
- Secretary: No! Please, don't!!
- (suddenly, the ground explodes beneath Zeus, sending him away. We see Terra descending to the area)
- Maxie Zeus: Who dares disrupt the execution?! (notices Terra) Gaia?! You dare return from Tartarus where you and your twelve Titans were supposed to be imprisoned?!
- Terra: First off, the name's Terra, not "Gaia". (Zeus shoots lightning at her, but she keeps walking while absorbing the electrocution) And secondly... (creates a rock gauntlet for her fists and punches Zeus, rendering him unconscious) ...you call this an "execution". But I call this a reckless pointless bullying. Which only a tyrant would take pleasure of. (addressing to the frightened couple) It's okay. I'm here to help.
- Secretary: We noticed. Thank you so much, huh... Terra. Right?
- Terra: Yes. That's who I am. (Terra creates a large stone pod to carry the couple to far away from the building) (narrating) Quite a wonderful experience, huh? My first real day as a solo fighter, and I did it just fine so far. But that's just the middle of the story. (flashback scenes about the events of Justice League: Knights of Rao episode "Lost Girl" and Teen Titans episode "Terra" play) Once upon a time, there was this young little princess named Tara Markov, who was hoping to live her dream of becoming just like the superheroes who inspired her as a child. This dream was almost ruined when a self-proclaimed "god in human form" took her father's life by using one noble hero as a bomb... and at the same time when one greedy tyrant framed the Justice League for crimes they did not commit. And sadly, there was nothing that princess could do. Not because of another psychopath's daughter, who strpped her off her memories and caused her to lose control of her powers. She ran to many... including the Teen Titans... who could maybe give her some help with her condition. But that psychopath stood in her way again and again, offering to be her "teacher"... but in fact, he was just planning to use her like he once tried to do with the Titans' leader. And there came the Man of Steel... the Last Son of Kryton... Metropolis' almighty guardian... and Earth's mightiest symbol of hope... With one single star... her problems were solved. She remembered everything. And with those memories back in her mind, and the training that mighty hero gave her, she now has one goal: to hunt down every single tyrant in the planet, and make them suffer a thousand times more than the Justice League ever did.