Carol was created by Impulse creator Mark Waid and Humberto Ramos.
Important Story Arcs
Carol befriended Bart when he first came to Manchester. Carol is the only one of his friends who knew his dual identity. She and Bart have shared secrets, plans, and even an accidental first kiss(followed immediately by hysterical laughter). Carol and Bart began to realize that they felt more than friendship with each other. Carol was kidnapped into the 30th century (later followed by Bart) by her future self to change what she has done in the future. The future Carol invented a "hyper-ray" that could enhance a human's speed to two-thirds of Bart's speed for Bart's uncle who happens to be an evil dictator of that time. Bart and his future-self tried to stop President Thawne's (Bart's uncle) plans but failed to change anything. So Carol chose to stay in the future longer with Bart leaving to go back to the present to save Max and his daughter, Dr. Helen Claiborne from a madman murderer.
Bart had told Max that he and Carol started falling in love and that he was terribly upset about Carol having to stay in the future. Carol along with Bart's mom, Meloni Thawne, had adventures in the future. Until Bart found Carol and informed her that her sacrifice was unnecessary and he took her back to the present. Carol returned to her family in Manchester. She and Bart agreed to remain friends despite their distance (Bart was living in Denver at the time with Jay Garrick and Joan Garrick).It is unclear whether they stayed in touch.
But during Bart's trip through time as the Black Flash in Flashpoint, Bart saw his life flash before his eyes, including his time in Young Justice, his brief time in the Legion of Superheroes, his moment he hugged his mother, and his first kiss with Carol.