Answer:
Following Yvonne through the house; we can see the obvious differences between Driss' dark black and functional clothes and the elegance of Philippe's environment. Deeper within Phillipe's house there is a large painted mural with a piano; further indicating the class difference.
Step-by-step explanation:
Both men are seen as outsiders, not normal, untouchable as the title says. Philippe is an untouchable because of his physical disability and Driss is an untouchable because of his socioeconomic disability. Although they are very different, they are the same. It is this that binds them together in their odd friendship.