We have the Narrator summarizing social personality after first reporting what his family knows and thinks about Charles Swann, thereby creating him. This is 3rd person narration—the speaker is the Narrator.
But then, even in the most insignificant details of our daily life, none of us can be said to constitute a material whole, which is identical for everyone, and need only be turned up like a page in an account-book or the record of a will; our social personality is a creation of the thoughts of other people.
Swann's Way Vol. 1 Marcel Proust 1913 translated by Moncrieff, Kilmartin and revised by Enright, p. 23.
Below we have 1st person narration; the speaker is also one-in-the-same but he is reflective, and a more mature Narrator—it is a different time. He speaks about what he knows of the real and imaginary Albertine. You are inside the thought process of the Narrator.
What did I know of Albertine? One or two glimpses of a profile against the sea, less beautiful, assuredly, than those of Veronese’s women whom I ought, had I been guided by purely aesthetic reasons, to have preferred to her. By what other reasons could I be guided, since, my anxiety having subsided, I could recapture only those mute profiles, possessing nothing else? Since my first sight of Albertine I had thought about her endlessly, I had carried on with what I called by her name an interminable inner dialogue in which I made her question and answer, think and act, and in the infinite series of imaginary Albertines who followed one after the other in my fancy hour by hour, the real Albertine, glimpsed on the beach, figured only at the head, just as the actress who “creates” a role, the star, appears, out of a long series of performances, in the few first alone. That Albertine was scarcely more than a silhouette, all that had been superimposed upon her being of my own invention, to such an extent when we love does the contribution that we ourselves make outweigh—even in terms of quantity alone—those that come to us from the beloved object.
Within a Budding Grove Vol. 2, Marcel Proust 1919 translated by Moncrieff, Kilmartin and revised by Enright, p. 597.
"Social personality" makes sense of how characters in the novel change viewed from different points and persons. On p. 698 of Within a Budding Grove there is more 1st person narration (in the voice of the Narrator) talking about the real and imagined Gilberte and Albertine. Proust's definition of social personality is of great import to the reading of the novel and entering his fictional world. There is little fixity in real life and less in fiction factoring in unreliability both real and imaginary.