In the course of my research on Descartes I stumbled across the book "Three Reformers: Luther, Descartes & Rousseau" by Jacques Maritain. His remarks about personality are quite interesting. He gives a quote from Reginald Garrigou-Lagrange, who says,
"the full development of our poor personality consists in losing it in some way in that of God, Who alone possesses personality in the perfect sense of the word, for He alone is absolutely independent in His being and action. (p. 24-25)"
He says, a little bit later, "But did the saints set out to develop their personality? They found it without seeking it, because they did not seek it, but God alone. They understood that their person, just in so far as it was person, in so far as it was free, was complete dependence on God, and that the inner mastery over our acts which we cannot resign to man or angel they must deliver into the hands of God, by Whose Spirit they must be moved in order to be His sons. (p. 25-26)"
Earlier he noted that a person is a complete substance that is rational in nature and is the source of its actions (p. 19). Personality, then, is the spiritual side of us, the intellectual or rational side of us. As such we should not be seeking to find our personality in others, or in what we do, but in God alone.