Teela Brown is a fictional character created by Larry Niven in the Ringworld novels. Teela was a member of the crew recruited by Puppeteer Nessus for an expedition to the Ringworld. Her sole qualification was that she was the sixth generation of a line of ancestors born by virtue of winning a Birthright Lottery. The Puppeteer saw her as the product of a program of breeding humans for luck, and hoped she would bring luck and success to the entire expedition.
Teela is a descendent of a former lover of Louis Wu. Her age in Ringworld is given as twenty, though there are conflicting data in later books. She joins the Ringworld expedition, then becomes separated from the group. She meets a Ringworld native called "Seeker," and she decides to remain on the Ringworld with him while the remainder of the crew returns to human space. In "The Ringworld Engineers", when Louis Wu returns to the Ringworld, it is revealed that Teela has become a Pak Protector, who manipulates the characters into killing her to prevent her Protector instincts from keeping her from saving the Ringworld from its inherent structural instability.
Further details of her life become sketchy as the Ringworld story continues through three more novels: her story becomes a matter of guesswork and deduction, and are subject to retconning from one work to another. The influence of Teela's "luck" is a significant factor in the story.
According to the story in Ringworld, Puppeteers intervened (indirectly) with the birth control laws of Earth five generations previously. Under the system they caused to be adopted, the right to reproduce was strictly limited: with some exceptions, everybody was entitled to reproduce exactly once. This did not result in a replacement rate of fertility, so the system also included a Birthright Lottery whereby any person could enter and win the chance to reproduce more often. The Puppeteers set this up specifically as a program of breeding human beings for luck. They believed luck to be a genetic (thus inheritable) psionic ability, and they regarded humans as unusually lucky to begin with. "Your species has been incredibly lucky. Your history reads like a series of hair-breadth escapes ..." Nessus says to Louis.
In Ringworld's Children we learn that Teela Brown and Louis Wu had a child. The child remained on the Ringworld after the Fringe War was brought to an end. Louis speculates that it might be Teela's genes that are lucky, not Teela herself.
The existence and nature of Teela's luck is debated back and forth by the characters throughout the four-book series. For most of the story, Louis believes Nessus has only found a statistical fluke, the extreme end of the bell curve, the person for whom the toast has always landed jelly-side up. (Indeed, the one who has never been unlucky enough to drop a slice of toast in the first place.) By the end of Ringworld's Children, however, Louis (who has been a hyperintelligent Pak Protector but is no longer) says he believes the luck could be real. He sees no other explanation for the appalling coincidences that have swirled around her life and that of their child.
Niven has described the problems that such a character and such a trait pose to his story and to his fictional universe. He calls it "Author Control" to illustrate the plot and story limitations it imposes on the creative process. The story "Safe at Any Speed" is set in a time when the Teela Gene is more common among humans. Niven says there will not be more stories from this time: "Stories about infinitely lucky people tend to be dull. This clearly indicates that the author believes Teela's luck to be genetic and inheritable, regardless of what the characters think.
Teela Brown's "luck" has often been criticized as a deus ex machina, although it was not used as such in Ringworld. Louis Wu specifically points out to Nessus that what is lucky for Teela could be dangerous to her companions. The concept has also been criticized on logical grounds; the usual reasoning is that if "good luck" were truly a genetic characteristic, one wouldn't need to breed for it. As the ultimate survival trait, it would automatically become the dominant characteristic of the human race. The supposed breeding method to get a lucky human, selecting five generations of people who win only one contest has also been ridiculed, though the story describes all the winners as having unlikely ("lucky") experiences. Niven's response of changing the power to "lucky genes" rather than individuals has lessened these arguments, since as long as a person has at least one surviving offspring, it could still be said that their bloodline is "lucky" from an evolutionary standpoint, even if that person suffers or dies.