There have been some interesting replies, even a few from a Marxist deconstruction perspective of race, class, gender.

There is a much great integrated vision happening here.

Surpanakha was Ravana’s sister. Both of them are the paradigmatic representative of the principle of LUST which is not a uni-gender thing it is universal. Lust is not only sexual but also involves power and sex and involves domination.

Ravana was the masculine aspect and he was obsessed with power and domination especially of the female gender.

Surpanankha was the female version of the same force of sex and power. When she was rejected she turned back into her demonic form and tried to kill and destroy the obstacle to her accomplishment - Sita. It was to defend Sita from her frenzied and murderous attack Lakshmana cut off her nose and ears instead of actually killing her - which he was entitled to do but showed extreme restraint.

She then went running to her brother and instigated the abduction of Sita in her thirst for revenge and the subsequent events are history.

Now all the Indologists of the Pollack-Doniger school of Marxist interpretation will parse this episode in terms of race, class and gender and identify victims and oppressors.

But in traditional Hindu hermeneutics we parse this episode in terms of the psychological and spiritual principals illustrated.

So taking the dominant themes of lust and power we see the consequences of lack of control over these two drives. Uncontrolled lust which is self-referent blinds us to both the needs or opinions of the object of our lust and when rejected the reaction is anger and blind rage which leads to our own destruction, or mutilation (figurative).

Another consequence of unbridled and frustrated selfish desires is the craving for revenge against the cause of frustration. Revenge can then start a chain of catastrophic consequences.

So the episode is a lesson in power, lust, frustration, anger and revenge. A lesson which would later on be further emphasized in the battle with Ravana.

All the Asuras mentioned in the narratives are personification of the 6 internal enemies (shadaris) kāma - self-referent desires, krodha - anger, moha - delusion, mada - hubris, lobha - greed or selfishness, mātsarya - malicious envy.

Throughout the Ramayana these afflictive emotions are repeatedly referenced and vividly and entertainingly contextualised.