He wants to marry a fat women because if he made a mistake, he needed to run away she should not be able to catch him.

Introduction:
In the story "The Snake and the Mirror" by Vaikom Muhammad Basheer, the author expresses his desire to marry a fat woman. The story is set in a doctor's clinic where the author finds himself in a difficult situation after a snake enters the room. While the story primarily focuses on the author's encounter with the snake and his subsequent fear, it also briefly mentions the author's preference for a fat wife.

Reasons for the author's preference:
1. Social acceptance: The author desires a fat wife because it is considered socially acceptable and desirable in his culture. In some societies, having a fat wife is seen as a symbol of prosperity and good health. It may also represent fertility and abundance.

2. Physical attraction: The author may find fat women physically attractive. Beauty standards vary across cultures, and some individuals may prefer curvier or fuller body types. The author's personal preference leans towards a fat woman, which could be based on his own subjective taste and attraction.

3. Comfort and warmth: Fat women are often associated with being warm and comfortable to cuddle with. Their body size may provide a sense of security and physical comfort for the author, especially during the cold nights or in times of distress.

4. Perceived nurturing qualities: The author may have a belief that fat women possess nurturing qualities. In some cultures, fatness is associated with being well-fed and having the ability to provide for others. The author might desire a wife who can take care of him and provide a comfortable home environment.

5. Challenging societal norms: The author's desire for a fat wife could also be seen as a rebellion against societal beauty standards. By openly expressing his preference for a fat woman, the author challenges the norms and expectations imposed by society, which often prioritize slimness as an ideal.

Conclusion:
The author's desire for a fat wife in "The Snake and the Mirror" is influenced by societal norms, personal preferences, and perhaps a desire to challenge conventional beauty standards. It is important to note that the story does not delve deeply into this aspect, as the main focus remains on the author's fear of the snake and his subsequent actions.