Servine's legs are often considered to be a symbol of innocence, for other snakes, such as Ekans and Seviper, must spend their whole lives slithering low to the ground to hide from prey, and Servine too lose their legs when fully evolved. But Servine are grass pokemon, capable of photosynthesizing their food, and their green color allows them to easily hide themselves from predators in tall grass; their lives in the wild were an idyllic Eden, free from the cruelties of the wild and of civilization.
Servine are said to remain in this form until they commit a single act of evil, at which point they evolve into Serperior, but Arceus (or in some tellings the swords of justice) steals their legs as punishment. The evil need not be horrific, and can be as simple as challenging an unwilling pokemon to battle, or eating with one's mouth instead of subsisting on sunlight. The stringent moral codes demanded to maintain their legs were difficult to uphold, and the power of full evolution – even a legless one – has always been a temptation in itself.
Some have seen in Servine's life cycle a metaphor for the corruption of adulthood, for human children are thought to live wholly innocent lives. But in truth, human children are often unkind, and a few remarkable human adults live lives wholly free of wrongdoing; it is the societies and cultures humanity has built, not their own biology, which ensure that few human individuals reach their final stage without harming anyone else.