The show is about a white collar con artists, Neal Caffery, who gets caught and forced to work for the FBI catching other crooks. Introduced in the first episode as an agent who wouldn’t fall for Neal’s charms, Diana Barrigan is a dedicated FBI agent.
She leaves after the first episode but comes back in season two to replace the less entertaining agent who’d replaced her to start with. Diana met her girlfriend, Christie, in a pottery class, but the move back to New York City takes its toll on their relationship. Wonderfully, Diana’s role isn’t based on her being a lesbian.
Her pregnancy in season five was written in to explain Marsha Thomason’s real-life pregnancy.