What effect does meeting the convict have on Pip? What are Pip's feelings for the convict, his fears? Does he want to keep his word?

The young Pip is frightened of the convict. He feels very guilty too about helping him, as he knows his society would consider it a sin and that Mrs. Joe would be angry. Nevertheless, he shows himself to be a compassionate and kindhearted boy. He goes above and beyond the convict Magwitch's expectations in bringing him bread, a rind of cheese, half a jar of mincemeat, brandy, a meat bone, and a "compact" pork pie, as well as the file he needs.
When Pip gets to Magwitch with the food, his guilt at stealing makes him feel he is about to be caught at every moment. Nevertheless, he shows empathy towards this man, noting how very hungry he looks and how he is shivering with cold. In turn, Magwitch, realizing that Pip has a kind heart, thanks him for the food.
As he does throughout this novel, Dickens goes back and forth between Pip experiencing events as a young boy and Pip as an adult thinking back in a more mature way on the events he experienced as a young boy. In this part of the novel, we see Pip experiencing Magwitch solely as a child would—as a fearsome, bigger-than-life, almost supernatural creature who could hurt and kill him. But, as Dickens adds complexity, Pip also sees a suffering person, one in need of food, shelter, and comfort. Pip views Magwitch with a child's eyes and sees not a criminal to judge, but a suffering human who is both in need and also frightening, as a wounded animal would be. Pip doesn't turn away from the need, despite his fear and guilt. We as adults can see how very desperate and vulnerable Magwitch is, on his last legs and no real threat at all. He has more to fear from Pip, than Pip does from him, but the child can only see through the child's eyes.