Tara Markov should have lived a privileged life, being born the daughter of royalty. But as she was the illegitimate daughter of King Viktor Markov of Markovia and an unknown woman who died in childbirth, she was hidden from public view and knowledge, as her existence would place a black smear on the royal family. She was placed in the care of Markovian scientist Dr. Helga Jace, who performed experiments on the child, and Tara was given incredible Earth manipulation powers (these powers were later also given to her brother, Prince Brion, a.k.a Geo-Force). Once she got these abilities, her father had her shipped off from Markovia and sent to America, all to prevent her identity from being discovered. Perhaps it was the rejection from her family, or perhaps it was the genetic manipulation which granted her powers, but Tara exhibited signs of mental illness from a young age, believing her powers made her better than ordinary people, and that they should all be subjugated.
While still in her early teens, Tara became a metahuman hitwoman now using the codename "Terra." It was during this time, when she was about fifteen years old, that she encountered Slade Wilson, better known as Deathstroke the Terminator, a well-known and highly regarded mercenary. She entered into a physical relationship with the much older man, and was then contracted by him into joining the Teen Titans as a spy. Her mission was to infiltrate and gain the trust of the team, so she would find out their secret identities and other personal information, information which Deathstroke would use to eventually defeat the Titans.
The Teen Titan named Changeling (formerly Beast Boy) first encountered Terra when she was threatening to destroy the Statue of Liberty, and later, robbing a bank. She told Changeling that all of these acts were things she was being forced to do by a group of terrorists, who were holding her parents, the King and Queen of Markovia, hostage. When one of the terrorists revealed that her parents had indeed been killed, Terra no longer had to commit crimes for them, and now found a home with the Teen Titans. The entire story was fabricated of course, and the “terrorists” worked for Deathstroke. Although many of the Titans still had questions about Terra, and saw holes in the backstory she had given them, Changeling instantly developed feelings for the young woman, although at first, she did not seem to reciprocate.
After some time as a member of the team in good standing, she began to show some affection towards Changeling, but it was all an act. Soon, the Titans revealed all their secrets to Terra, and she wasted no time in giving that information to Deathstroke. He used his knowledge to kidnap the Titans with Terra's help, and send them to his employers, the criminal organization called the H.I.V.E. Once captured, Terra revealed the truth about who she really was to them, all of whom were shocked that the young girl they saw as a friend was a ruthless killer, and had played them all for fools. None was more hurt by this revelation than Changeling, who had fallen in love with Tara, and was convinced she was being coerced by Deathstroke. In return, she did nothing but taunt him as the rest of the team as weak "do-gooders."
Helping rescue the Titans from the H.I.V.E. was Deathstroke's own son, Joseph Wilson, also known as the metahuman Jericho. He had the power to possess others, and while in control of his father's body, he used it to subdue Terra. Not realizing Deathstroke was possessed, she saw this as a betrayal, and quickly flew into a rage, unleashing all of her powers at once, against everyone. She destroyed the HIVE base, and eventually she accidentally killed herself as well. It was Changeling who discovered her body in the rubble. She was given a proper Teen Titans burial, and her status as a traitor was not revealed to the public, not even to her own brother.
Post CRISIS ON INFINITE EARTHS
The sting of Terra's betrayal hurt the Titans for years. Even though they let Jericho join the team as her replacement, they were slow to trust again. After the scars of Terra had finally healed for the team, she seemingly returned from the grave, as the Titans were confronted with a girl who had the exact same powers and appearance as Terra. She was actually a doppelganger of Tara Markov's, and had been sent back in time with a group called the Team Titans, to kill Donna Troy before she gave birth to a son, who would grow up to rule the future as the despotic Lord Chaos. They were able to stop this future from happening without killing Donna, and the Team Titans remained in the present.
This Terra developed a crush on Changeling, but he did not reciprocate those feelings, as she looked too much like the original Terra. Eventually, he began to realize they were indeed separate people. The future that Terra II hailed from was wiped away during the time crisis called Zero Hour, and all but one of her Team Titans teammates, Mirage, were wiped from existence. It was revealed that Terra II was really from the present, and her origins were more of a mystery to her than ever. She joined the regular Titans team until they disbanded. Not long after, she visits Geo-Force, and he submits Terra II to genetic testing, which reveals that her DNA matches his sister, the real Tara Markov. However, Geo-Force, having since learned of his sister's betrayal, lied to Terra II and told her that she was not a match for his sister, for her own peace of mind.
It was finally revealed that Terra II was a member of the subterranean race called the Stratans, who was granted geokinetic powers by a substance unique to that people called quixium. Because her powers were so similar to Tara Markov's, DNA from the original Terra was mixed in with her own, so she could fully pass as Tara Markov in the world above. But the process by which she was given Markov's appearance also wiped her memory. She eventually died in battle, when she and several heroes attempted to stop the rampage of Black Adam, an event later referred to as "World War III."
Post INFINITE CRISIS
After the second Terra's death, a third Terra emerged. Named Atlee, she wore a different costume than the previous Terras, and had jet black hair. However, her power set was the same as theirs. Atlee also came from the intra-terrestrial race of people that lived deep below the Earth's surface called the Stratans, just as Terra II did. Her race's culture and survival was linked with the Earth itself, and they occasionally created a champion to send to the surface world to protect the ecosystem.
After Terra II died, Atlee was given geokinetic powers also based upon the genetic template Tara Markov. Taking human form, she came to the surface world and began a career as a Super-Hero, and the world was introduced to Terra III. She first made herself known by teaming up with Supergirl, and later, by becoming a sidekick to Power Girl and residing in Manhattan.
The original Terra finally did return, in a way, when the BLACKEST NIGHT event spread across the galaxy. During this event, Tara Markov’s corpse was revived by the Black Lantern Corps, and she was used as psychological warfare against the Titans, particularly Beast Boy, who had never come to terms with his feelings for her, or her ultimate betrayal. She is ultimately defeated and returned to the grave, along with all the other Black Lanterns.
After the events of 2011's FLASHPOINT, reality was altered, and the previous history of Tara Markov was wiped from existence, including her death. A new Tara Markov emerged in this new timeline, with the exact same powers and appearance as the original. Captured by the group called N.O.W.H.E.R.E, she eventually escaped with other young metahumans, and under the guidance of Caitlin Fairchild, these young heroes called themselves the Ravagers. Among the other members of the Ravagers was Beast Boy, who developed feelings for Terra just as in the previous timeline. Most recently, Terra joined the group called Defiance, led by Deathstroke. Considering their relationship in the previous timeline, this partnership might not bode well for the DC Universe.