The character of Camille in this novel is interestingly defined to a great extent by his relationship with his mother, the over-protective Madame Raquin. From birth, his sickly disposition has caused her to care for him and love him beyond the realms of normal expectation, and this causes him when he grows up to want to seek his own independence and to live his own life away from her stifling affections:
At eighteen, having nothing to do, bored to death at the delicate attention of his mother, he took a situation as clerk with a linen merchant, where he earned 60 francs a month... She wanted to keep him always with her, between a couple of blankets, far from the accidents of life.
Naturalism was a literary movement that sought to combine gritty realism with the scientific ideas of thinkers such as Darwin with his Theory of Evolution to seek to explore the way that character was shaped so much by environment and setting. In the case of Camille Raquin, his character is shown to be shaped by both the squalid conditions in which he was raised but also by his relationship with his mother, both which served to create a man who was spoilt and lacking in imagination and independence. In short, precisely the kind of man who was most unsuited to the character of Therese and her desire to extract more from life.