"The first exercise my students have to complete is to confront their queen bee...but you find them and squash them."
Little is known about Paul's past, although Garcia mentions that he had "a major mullet" going on. At some point prior to 52 Pickup, he established a pickup artist class program, which became rather successful.
The BAU first meet Paul, who calls himself "Viper", at one of the pickup classes he teaches in Atlanta. He is immediately attracted to Prentiss, whom he flirts with diligently. He also makes it a point to tell Morgan that he destroys alpha males like him, mostly for fun and sometimes profit. Due to his personality and drink receipts that gives him an alibi, he is immediately ruled out as a suspect, but is kept under a watchful eye. The team realizes that the unsub used some of the same lines that Paul uses, thus it is obvious that he learned his "tricks" from Paul.
As Morgan and Reid pass out fliers at a local club, Prentiss and Todd keep tabs on Paul to watch how he works. Paul eventually spots Prentiss and approaches her, saying that it's his "lucky day". After unsuccessfully flirting with her, Agent Todd approaches the table. Paul tries flirting with her also, but is quickly shot down. He then explains that Todd is what he and other "pickup artists" call a Queen Bee; basically an Alpha Female. He explains that the first assignment his students must accomplish is to confront their Queen Bees, and "crush" them. Hearing this, the two Agents make the connection between the unsub and his first post-escalation victim, Vanessa Holden. It is presumed that Paul simply went back to teaching his "class".