Koriand'r (currently known as Starfire) is the main heroine, the sister of Blackfire and Dick Grayson's love interest. She was the member of the Teen Titans.
Starfire was born and raised on the distant planet Tamaran before arriving on Earth and joining the Teen Titans. The Tamaraneans are an emotional race who see feelings as the force that drives their very livelihood. In fact, it's their emotions that fuel their natural abilities of flight. Because of this, Starfire is inherently the most sensitive member of the Titans.
Starfire was cared for as a child by Galfore. Starfire's only family of which we know in the series is her evil big sister Blackfire. Later, in the comic Teen Titans Go, it's revealed she also has a younger brother named Wildfire, who was sent away when the Gordanians attacked Tamaran, and that her parents died from grief after she was traded as a slave by Blackfire to the Gordanians in order to bring peace to war-torn Tamaran.
Starfire came to Earth as Koriand'r, an alien princess being transported by Gordanians, in exile as a slave to the Citadel. Through the use of her innate Tamaranean strength, she broke free from the brig aboard a Gordanian ship and landed in Jump City. While attempting to free herself of the handcuffs with which she had been laden, she ended up both destroying buildings and cars, and running into four young teenagers with whom she would later fight crime.
Raven suggested that fighting may not be the answer, and only then did Robin notice the handcuffs. Carefully, he talked the mysterious girl down and took off the handcuffs. She grabbed and kissed him to learn the English language, and warned him to leave her alone if they do not wish to be destroyed. (This falls in line with how Tamaraneans learn language through lip contact.) And then Cyborg said that she knows how to leave a mark.
Once freed, she sought out food in the form of popcorn and candy at the local video store.
Having been tracked by the Titans, she reunited with them and fought off the wave of Gordanians sent to recapture her. Angered at Lord Trogaar's promise of destruction, she yelled at Robin, reminding him that she told him to leave her alone. The two got into an argument, but the situation was quickly defused after they apologized to each other, and the decision was made to work as a team to save the city from the Gordanians' particle weapon. The five teenagers founded the Teen Titans shortly after.