Kevin proposed the sexual pact in the original film, and was the only one who started the series with a steady girlfriend. At the time he was dating Vicky (Tara Reid), a nice girl who was unwilling to take the next step in their relationship. The two ended up sleeping together in the end, with the assistance of a book on sex ed provided by Kevin's older brother.
After his break-up with Vicky in the original, Kevin spent the sequel pining for his former girlfriend and retrying to rekindle the romance. But it was all in vain, as she ended up staying with another guy, leaving Kevin as heartbroken as ever.
In the third film, Kevin played a minor role as a groomsmen in Jim's wedding. Jim's bachelor party got out of control - and Kevin ended up tied to a chair because of it- but he had little else to do in the film.
Kevin begins Reunion as a married man who now spends his nights watching Real Housewives. He is also a desperate man, who longs to spend a weekend with the boys.