Pre-New 52 (1976-2011)
After Karen and her boyfriend, Mal Duncan, joined the Teen Titans, they transferred to Titans West before the short-lived team dissolved. The reprieve from duty allowed Karen and Mal to focus on their relationship, and the two decided to retire from superhero life and get married. At this point, Karen took a job with S.T.A.R Labs, working on the development of non-lethal weaponry.
Both Mal and Karen briefly returned to active duty with the Titans West during the JLA/Titans crossover event, THE TECHNIS IMPERATIVE (1998-1999), but resumed their civilian lives once the Technis threat had been dealt with.
It wasn't until the events of 2005-2006’s INFINITE CRISIS that Karen officially returned to her life as Bumblebee. The Crisis placed both her and Mal in danger and in need of rescue. Adam Strange and one of his Zeta Ray beams eventually saved her, with the beam teleporting Karen out of harm's way. But there were side effects—the beam affected Karen's physiology. The end result? Karen was shrunk down to six inches.
The changes stuck for Karen, and she was forced to seek help from the scientists of the superhero community to reverse her newfound problem. Her search led her to the Doom Patrol and its leader, Dr. Niles Caulder, who solved her dilemma. During this time, Karen and Mal both worked with the Doom Patrol.
New 52 and Rebirth (2011-Present)
Following the continuity-reshaping events of 2011’s FLASHPOINT, Karen was reintroduced to the DC Universe as a former member of the Titans for the first time in TITANS HUNT (2015). She and Mal were married in this new continuity, though retired from their roles as superheroes.
Karen, however, returned to active duty as Bumblebee, despite becoming pregnant with her and Mal's child. She gave birth following a confrontation with the Titans’ very first foe, Mr. Twister.
Following the events of 2016’s DC UNIVERSE: REBIRTH #1, Bumblebee did not immediately return to the active Titans roster. Instead, she went back to work at S.T.A.R. Labs while raising her child. It wasn't until the Fearsome Five launched an attack on her friends that Karen was pulled back into action, albeit temporarily, in 2017’s TITANS vol. 3 #10.