To accurately explain Stephanie's transformation into one of the coolest female comic book heroes-next to Supergirl, who she's also friends with-a bit of her background has to be told. She first debuted as the daughter of a lesser known Batman villain called the Cluemaster in Detective Comics #647-649 in a 3-part mini-arc that showed she will become a hero who's sole purpose-at the time-is to 'spoil' her father's plans, hence the eventual debut of the Spoiler. When her father was put away, both Batman and Robin-Tim Drake as the then-holder of the identity in question-persuaded her to hang up her cape.
Barely a year later in real life time, she was introduced in the pages of Robin as his foil/love interest. She remained in his book as a supporting character for well over a decade, eventually becoming the first Girl Wonder-in comic canon, as Carrie Kelly is considered an AU Girl Wonder-to don the identity of Robin for a time until her editorially-dictated death in late 2004. Fan involvement and controversy surrounding her not getting a memorial in the Batcave a la Jason Todd eventually convinced DC Comics to bring her back in 2008. After a few appearances here and there, she was revealed in August 2009 to be the new Batgirl in Batgirl #1 as then-Batgirl Cassandra Cain had opted to give up wearing 'his' symbol in the wake of Bruce Wayne's 'death.' Since then, 12 issues have been released-said 12th issue coming out just last Wednesday-and she has proven that she does belong among the Batfamily.
One of the people she had to convince that she belonged-other than Dick Grayson, Damian Wayne and Barbara Gordon-was Tim Drake-Wayne, her ex-boyfriend. Tim's journey has literally taken him around the world and back again as he is the only one who had believed-at the time-that Bruce Wayne wasn't dead following the important Batman R.I.P. and Final Crisis events of 2008-2009. With Dick as the new Batman, he purposefully took the 'job' of Robin from Tim and gave it to Damian; his reasoning was that Batman & Robin were a mentor and protege teamup, and he considers Tim to be an equal. Tim was less than pleased but reluctantly gave up his former identity and took on the name-that he believed to be tarnished due to recent events involving Jason Todd and one of his own foes-of Red Robin. (Jason had come across the costume in what was possibly a pre-Kingdom Come era, assumed the role for a time in various other worlds but immediately gave it up upon returning to his own; Tim's foe-known now as Anarky-came across it and used it for a time against him until Tim had taken it sometime later.)
When Tim did find evidence that Bruce was still alive, but lost in time, he returned to Gotham City and teamed up with ex-girlfriend Stephanie-in real time this happened in the month of March 2010-to prevent Ra's from destroying everything Bruce had built; Tim made sure that didn't happen and earned Ra's respect in the process. (Before then, Ra's has only called Bruce by the moniker of Detective, and in Red Robin #12, released in May 2010 he called Tim that...before kicking him out of a window.) Recent events have Tim and Stephanie protecting Gotham in their own way via separate adventures-Tim has set up a hit list for Gotham's Rogues Gallery, which will allow him to topple 'dominoes' and by arresting one villain will set up another one for him to bring down-the apprehension of one target will lead directly to the next, as Damian put it. Next month, Stephanie will get an opportunity to take on one of Batman's more...slippery villains in Clayface.
"Good call, Marcia." - Tim Drake
"I know, Cindy..." - Dick Grayson, Red Robin #14
"This is gonna be the beginning of a beautiful friendship!" - Stephanie Brown, Batgirl #12