Pip is a quiet, introspective kid. He is easily eaten up by guilt, and he is compassionate about others. These traits are reveled through direct and indirect characterization.
Direct characterization is when the narrator, in this case an older Pip, talks about himself. Indirect characterization is when the others talk about the character or information about the character comes from his actions and what he says.
The older Pip thinks the younger one is fairly foolish. For example, Pip comments that, “I drew a childish conclusion that my mother was freckled and sickly” (ch 1, p. 4). This is direct characterization. As an adult, Pip looks back at his childhood self with a combination of humor and derision.
Pip sometimes directly describes his child-self.
I believe they were fat, though I was at that time undersized, for my years, and not strong. (ch 1, p. 5)
Pip tells us directly what he looks like, in response to Magwitch's accusation that he has fat cheeks.
Pip also describes his thoughts, feelings, and actions as a child. For example, when the convict Magwitch frightens him, the older Pip looks back on the experience.
I earnestly expressed my hope that he wouldn't, and held tighter to the tombstone on which he had put me; partly, to keep myself upon it; partly, to keep myself from crying. (ch 1, p. 5)
Although Pip does not say so, he demonstrates that he was actually a very intelligent and brave child. This is somewhat indirect characterization, because Pip is telling you about himself without directly describing himself. He is describing his actions, and we can infer traits from them.
Pip also talks about his fear and guilt, both of which seem to overwhelm his childhood.
Conscience is a dreadful thing when it accuses man or boy; but when, in the case of a boy... it is (as I can testify) a great punishment. (ch 2, p. 11)
Pip is also relatively brave when it comes to standing up to his abusive sister. When he hears guns on the moor and wants to find out what is going on, he persists in asking even though his sister is angry at the questions.
The older Pip is also thoughtful and compassionate to his younger self.
Since that time, which is far enough away now, I have often thought that few people know what secrecy there is in the young, under terror. (ch 2, p. 12)
Thus, most of the characterization of Pip is indirect, even though he is telling the story in first person. He describes himself and how he felt.