Kevin is one of Gru's most multi-talented minions and, thus, appears to hold a bit more influence and rank amongst all the minions, thanks to his historic role in leading them to a new and brighter future in the service of Gru.  He also has a passion for the game of golf, and has his own set of clubs and matching clothing for such occasions.  Of course, like all minions, he's rather mischievous and--occasionally--devious, and doesn't mind using his clubs for less-than-savory purposes (he also is pretty handy with their use as weapons). 

In the minions' darkest years, prior to their ever meeting and working for Gru, it is Kevin who decides to set out in search of new opportunities for he and his brethen, accompanied by Stuart and Bob.  They sought out the biggest, baddest villain to serve...finding themselves briefly (and tumultuously) in the service of Scarlet Overkill, the greatest super villain of the late 1960s.  It was during these misadventures that Kevin was briefly exposed to some radiation which made him grow to tremendous size (towering over many of London's row homes and low-rise buildings of the time)...a situation which also aided him in defeating Scarlet and her other henchmen.

Above: Kevin, temporarily tranformed to tremendous size by a dose of radiation (from an experimental device in Herb Overkill's laboratory), towers over the buildings of 1968 London as he rushes to the rescue of his buddies, Bob and Stuart.

(NOTE: Officially there are two Kevins in the Despicable Me franchise.  Each is an entirely different type of minion.  This particular Kevin appears much more frequently than his earlier counterpart...first being seen in Despicable Me 2, and then featuring in Minions as a primary character.  Thus, when people think of a minion named "Kevin", this is usually the fellow they're associating the name with.)