SuperFlash

SuperFlash is the het ship between Kara Zor-El and Barry Allen.

Canon
Kara and Barry meet when Barry's training to improve his speed and runs fast enough to cross the dimensional barrier to Earth-3, where he saves Kara's life. She informs his this was unnecessary and flies away, revealing that she's Supergirl. Barry follows and they collide, both realising that they're both superheroes. Barry enlists Kara's help to return to his earth, while Kara is thrilled to have a 'superhero colleague' with which to share understanding of her lifestyle.