Who is Brendan from Crank and what is their importance?

Brendan is the handsome lifeguard, Kristina meets at Wild Waters. The two go on a total of two dates before Brendan rapes Kristina, an act that results in prenancy. Although, Kristina intially plans to abort the baby, she changes her mind. Fortunately, Kristina's drug use does not affect her infant. The baby is named Hunter.