when did Tom Sawyer become self aware and not self centered anymore

I think that around Chapter 23 and 24 we can see a change in Tom. He had been wrestling with the moral conundrum of letting an innocent man, Muff Potter, go to jail or be executed. Tom had feared retribution from Injun Joe if he told the truth but, in the end, tells everything at the trial. Tom put the poor drunken wretch Muff Potter before his own interests. The last chapter gives us a Tom that is more self-aware. Although uncomfortable with the niceties of society, he at least accepts that he must play a part. We see this when he asks Huck to be respectable.