This is a broad question. You will get many different answers to it because of its wide nature. I might suggest that you repost it with different authors' contributions, as each author has their own style and their need to demonstrate different themes in their work. Having said this, I think that the one of the basic themes of Indian English poetry is the same theme present in Postcolonial literature, in general. There is a complex relationship between occupier and indigenous people. Indian English poetry reflects this complex and intricate relationship. On one hand, there is definite anger and resentment in the idea of a foreign power exerting so much influence and control in a land that is not theirs. The fact that the British resentment is so strong is natural. Yet, the fundamental challenge here is that the resentment comes about in the oppressor's tongue. Indian English poetry is unique because its expression of nationalistic identity is not done in a nationalist language. Rather, it is done in the language of the oppressor. This helps to make the construction of identity and the relationship that one has with the world a very complex one and something that dominates the genre. How does one recognize "the other" and criticize it, yet understand that it helped to bring out about its own articulation? It is a complex issue and one that is present in Indian English poetry. For specific reference points, I think that you need to specify certain poets and analyze how their relationship with "Indian" and "English" impacts them.