Pip is worried that he is going to get in trouble for fighting with the pale young gentleman.
Pip is concerned when he goes back to Miss Havisham that he is going to get in trouble for fighting with the “pale young gentleman” in Miss Havisham’s garden.
My mind grew very uneasy on the subject of the pale young gentleman. The more I thought of the fight, and recalled the pale young gentleman on his back in various stages of puffy and incrimsoned countenance, the more certain it appeared that something would be done to me. (Ch. 12)
He is sure that he is going to be arrested, because he is just a simple blacksmith’s nephew, and the pale young gentleman is much more important. He says, “I felt that the pale young gentleman's blood was on my head, and that the Law would avenge it” (Ch. 12). Pip generally worries about everything, and suffers from feelings of intense guilt.
When he goes back to Miss Havisham’s house, however, nothing happens to him regarding the fight. He doesn’t get in trouble for it, despite his deep, dark fears.
However, go to Miss Havisham's I must, and go I did. And behold! nothing came of the late struggle. It was not alluded to in any way, and no pale young gentleman was to be discovered on the premises. (Ch. 12)
In fact, much later he learns the pale young gentleman’s name. He is Herbert Pocket. He also learns the real motive for the fight. Herbert just enjoyed fighting! There was nothing personal about it. They become great friends.
This is another example of Pip’s guilt getting the best of him. He has a great imagination, and often it gets ahold of his guilt. Pip usually feels as if he is about to be punished for something, or dragged off to jail. The irony that he later becomes friends with the gentleman is a great Dickensian trick. It is also an example of his feelings of class inferiority, because he automatically assumed he was the lesser party.