Gleeson is a reporter and talk show host for "Gotham Live", a news channel in Gotham City. She resembles Batman supporting character Vicki Vale, as she also has red hair and works as a reporter (though Vale was a photojournalist).
Gleeson is often seen on the show in cameo appearances, reporting on crimes as exposition for the audience. She has been taken hostage a few times by criminals, but usually by accident. Most notably, she was kidnapped by Kyodai Ken in the episode "Night of the Ninja" and nearly discovered Bruce Wayne's double life during his conflict with Ken. She was also featured in the episode "A Bullet For Bullock". In the episode Harvey Bullock approaches her for help and implies that the two have a history together. Whether this was romantic or merely a friendship is never expanded upon. In the episode, "Lock-Up", moments before she is kidnapped by the titular vigilante, she is seen exiting a restaurant with Bruce, having just had dinner with him, but their dialogue implies that it was dinner over an interview about a Wayne Enterprises merger and not romantic.
When Batman: The Animated Series was revamped as The New Batman Adventures, Summer Gleeson was mostly absent. Instead, Jack Ryder was used as Gotham's exposition-speaking reporter, mostly to set up for his eventual transformation into The Creeper.
In the Batman Adventures comic book, she has been romantically pursued by Clayface and went on a date with him while he was in the form of a handsome young man. She is also pursued by Killer Croc in Batman and Robin Adventures. Croc tries to convince her to go out with him, but she is unaware of his affections. When he attacks Batman and Robin, she says he is acting like a monster, which causes Croc to turn himself in, allowing Batman to take him to prison.