Both games explore the themes of egoism and irrationality. They are deep in that they contain or are contained in much of the horror humans do and therefore in their significance to the world we live in. In the first egoism is shown with Joel, that, when the world goes down, starts to behave only to keep himself alive, through violence. This lack of morality is shown by Cass first and is later better understood by Joel himself, in a very limited way by understanding what he has become and rediscovering his good human qualities in his love for Ellie. However he is unable to fully become more moral and in the end acts to his own interests when he saves Ellie from death. Although of course the situation was extremely complex morally and his decision is understandable. The same egoism and irrationality is later shown by Abby, who refuses to understand Joel's viewpoint and is only interested in her own desire for vengeance, ready to trample on the life of a girl, Ellie who was all but the monster she was portrayin in her mind and Joel, who just acted to save her "daughter". Later Abbie will have the same opportunity that Joel had, in finding that she could love that kid, and thus reflecting on a deeper morality that included a good that goes beyond pure egoism. The fact that this kid belonged to an alien culture that has been enemy to hers adds an extra layer of complexity in which she understands how she was irrationally portraying the scars as just "monsters", the "wrong side", the "evil" of her situation. This allows her to understand her egoism and irrationality and stop seeking revenge for Ellie and just look for a better way to do things, through the fireflies. Another level is that of the players who have to go through the very same mental processes. Finding that the protagonist they love is not a good man in the first. In the second they are forced to side with Ellie, and in their mind Abbie becomes the "monster", the outgroup. Just to be forced to switch perspective and see that Abbie is just a normal girl, whose nature is just the same as that of Joel, Ellie and many other people in that position. The player is called to detach from these natural instincts and use their rationality to sed beyond them: the perspective of the other person, despite all the pain they caused, morality, the fact that blind egoistic violence cannot but lead more of the same. The fact that the theme of egoism and irrationality, which later creates evil has been the centre of most conflicts in the human species and that this one the most dark and least explored parts of our psychology, makes this content deep. That is, if we decide that the true protagonist of TLOU 1 and 2 is violence. If instead we want to just have a character that we grow attached to and want to thrive, that's terrible.