Dave is one of Gru's most trusted minions, skilled in the operation of mechanical devices and vehicles, but not terribly accomplished in the handling of weapons. He's also a fair hand at infiltration into enemy strongholds though, like most minions, he tends to be easily distracted from the mission at hand.
Of course, apart from his official duties (and in terms of personality), Dave is a gentle, friendly and altruistic little guy. He longs to own his own puppy, and is an affable and sociable individual who enjoys others' company. There is very little mischief or naughtiness in this particular minion.
Dave is also something of a romantic, and develops a substantial crush on AVL agent Lucy Wilde. He quickly realizes, however, that he has to give that up when Gru eventually falls in love with and marries her. There are no hard feelings between Dave and his boss, however...Dave happily performs lead on a cover of All 4 One's "I Swear" at Gru and Lucy's wedding reception!