Christy is filling two roles as both master of ceremony and soulmate to the bride. First year at Grinnell College the gods of housing put two triples of first year ladies across the hall from each other (and a third triple of first year dudes directly above them). Living across the hall from each other, Katherine and Christy realized quickly they are the same person and can read each other's minds. Christy has lived with Katherine (and Ian) at various points over the past 12 years, and has traveled on 3 continents with them. Future plans include living together again (or at least not on opposite sides of the country) and traveling to a fourth continent.
Liz and Katherine met while interviewing at UCSD. In fact, thanks to the psych department's penny-pinching they shared a bed that weekend (which is one way to jump start a friendship). Their friendship was renewed that fall, having both chosen to dedicate a not-insignificant portion of their 20s to pursuing PhDs in San Diego. They also spent a good portion of that time drinking beers, playing board games, and arguing about whether or not Katherine and Ian should get a dog.
Katherine and Julia met on move-in-day at Grinnell when Julia took up residence in the first year triple across the hall. Katherine was initially very intimidated by Julia (Katherine recalls being sweaty, disheveled, and overwhelmed at their first meeting, while Julia appeared calm, poised, and fabulous). While both sides of this first impression would prove accurate, that thankfully didn't stand in the way of them becoming great friends.
Katherine likes to joke that Brian is her favorite brother (also, her only brother). It's this sort of crack wit that Brian has stoically dealt with his entire life. For a good part of their childhood Katherine did not understand why she would ever need to make other friends when she had a playmate and friend living in the same house as her. Eventually, Katherine did make other friends, but this guy is still pretty great.
First year at Grinnell, Sean technically lived in the triple above Katherine, but he almost immediately became the de facto 7th roommate to the ladies of Dibble 2nd. Katherine can't actually remember their first meeting, as he has seemingly always been a happy presence in her life for the last twelve years.