Erica Marie Flynn first appears in Every Rose Has Its Thorn. She is a matchmaker who murdered her husband.
After meeting and marrying her husband John Flynn she ran his matchmaking business with him and made a lot of money. When John wanted to sell the business she killed him and set up an alibi with the help of Peter Clarridge, her assistant with whom she was having an affair. When CBI started investigating, Erica tried charming Patrick to control the investigation but failed. Although she wasn't able to seduce him, she did manage to make him reveal a lot about his feelings for his wife -- all captured on video tape and subsequently seen by Lisbon. Later Patrick tricked her into revealing she didn't care about Peter. As a result, Peter gave her up. She was confident that she would beat the murder rap and was eventually incarcerated for manslaughter.
Erica returns in the episode War Of The Roses when she calls Patrick Jane from prison claiming to have information about their current case. She convinces him to get her a short furlough from prison to help find the killer. He is, of course, suspicious of her the whole time, fearing she'll try to escape. Inevitably she gets Jane alone in a hotel room and seduces him. After the killer is found, she is picked up by a guard to be returned to prison but it turns out, the guard who picked her up was a fake and she escapes. She later calls Jane from a warm place and says that she is looking forward to meet him again.
Erica is a sociopath who uses her looks and charm to get whatever she wants in life like getting Jane to kiss her. She is playful and can be considered as smart as Jane is.
She is the "Irene Adler" to Jane's "Sherlock Holmes".