Well I'm extremely late to this thread but I would like to give my two cents. I firmly believe Chris to be an INFJ, as the commenter above has stated. I've seen somewhere earlier a person state they could imagine an abused INFJ to act the way he did towards his family. Well, Chris's family life included a large amount of abuse...if you would like confirmation of this look to the accounts of his older sister, Billie. The fact of the matter is, an INFJ whose Fe is threatened at a young age will turn their feelings inward and take other's issues out on themselves in a way that makes them push themselves away. I would gander that many INTJs would flat out tell the parents: I am leaving you and explain why. Cutting someone out via Ni-Te is direct and can be communicated without hardship because it is a positive way of extraverting a judgment. But Chris's decision to just leave them confused...mystified as to why their perfect genius child (Fe mask) dropped out of their lives. This is an extremely INFJ thing to do. To crave vengeance against those who have not treated others kindly, and to execute this by dropping them from their lives and making them ask why and saying they will never accept them back. Unfortunately, while the Ni-Ti "Door Slam" works fine with most people, for those who are extremely important in the INFJs life, all this amounts to is running away from problems. The fact, however, that after such long time Chris is willing to forgive his parents and re-accept them into his life shows how much he needs them and proves his idealism does in fact include others. INFJs HATE cutting people out of their lives, and after enough time most will try and forgive them because Ni allows them to detach from their feelings and find a new path to forge via extraverting feeling judgments. Aside from the story line of his relationship with his parents there are many other things which turn me towards this type:
I want to establish why he is NOT an INFP. Chris looks to be something of an Fi user because of his strong internal feelings, but does anyone think an Fi user would REALLY care about being a "bastard child?" An Fi-dom would not care what society would label him as. He would likely simply carry on believing "I have my identity, who the fuck cares." Fi doms don't do that questioning identity thing or walking over the planet looking for one...that's Fe users who want a stable sense of self. Do we also think an Fi dom, or an IXFP would be so driven as to actively work towards something like Harvard law school to make a parent happy AND take direct action in the world? This sounds much more J to me. A vision of some kind...that could only become disrupted in the INxJ if the Je function experiences turbulence. Another strong indication of Fe is, as the commenter above has stated, his decision to go out and hand food to homeless people in DC as a young kid. This demonstrates excellent people skills and, as his later travels would prove, the inherent ability to connect with everyone. And that is a key to showing why he is an Fe user and not an Fi user. He was able to take what he experienced and make everyone else feel it. He was able to introject into others and show them what they needed, not based on his own moral view, but on how he saw them. That is a beautiful example of Fe. And finally a (paraphrased) quote that simply speaks to his Fe: "God has placed enough in man's surroundings to fill his heart." In other words, there is so much love around that is always accessible to man. This idea of spreading the love around is the principal of Fe as opposed to Fi, which tends to form long bonds and consolidate on certain people into long unbreakable bonds. An INTJ would not have been able to connect as strongly as he did and then leave these people along the way. That is the irony of INFJ vs INTJ, the INTJ is actually capable of being more caught up in specific individuals, because they do not connect as much to the grander scheme of people and things around them.
The argument of Ni/Se vs Ne/Si to me is quite clear. There is nothing comfortable about what Chris does. He does not seek safety in regulation (Si) nor use this as a point of abstraction (Ne.) Do you remember the part of the story where Chris is at Emory and lives in a harsh environment in his dorm room, living in crates and spending his days not interacting with people as he had before? This is a great demonstration of the harsh nature of Ni, seeking Ti truth by cutting out emotion. An INFP would not do this, they would surround themselves in comfortable conditions in their most introverted loops because of tertiary Si. Chris is happy to go outside and work hard in the grittiest areas of the world and his travels in order to have a one on one experience with nature and reality. He plans out his ultimate adventure (Ni) which he is sure will allow him to come to a conclusion (Je). He sticks to the terms of this adventure so much that he gets himself in trouble and ignores the physical reality and his own necessities (inferior Se). He uses his experiences outside to funnel his understanding of the world (Ni). And perhaps the most interesting part is he comes to a final judgment via a Je function which is non other than Fe...that man needs to surround himself with other men to live a purposeful life. Chris goes away, isolates himself, and ultimately brings himself out of this isolation by making an external feeling judgment. While this is all too late, it only proves the importance of Fe in INFJs. If he had had this sense in the first place he would not have let his tertiary Ti pull him down to Se to the point that he took a difficult and life-costing expedition. Though one might say in a mythologizing of INFJs sense that he completed his ultimate quest for understanding in the world, as he came to his understanding of why others are important. Beautiful story really.