As a child, Sethu’s initiation into literature was through the books of the small village library at Chendamangalam, which had a fairly good collection of world classics. Though a voracious reader from his childhood, he was never in the forefront in any kind of literary or
artistic activities during his student days, at school or even in college.

The migration into the major cities of North India in search of a career, that too at a very young age of 19, was a major turning point in his life. It was a totally new world and a new terrain of experience for him and the exposure gained during his stints at various places
contributed substantially in transforming him into a different human being altogether, one who was capable of looking at the world around him with a new pair of eyes. The eagerness to delve deeper into the intricacies of the human mind, and to look at human predicament arising out of conflicts, with a greater degree of empathy, perhaps, helped him discover the writer within himself.

During his assignment in New Delhi in the mid-sixties, he had the opportunity to come into contact with a group of young writers, who were eager to move away from the past and were endeavouring to create a totally new trend in Malayalam fiction. By a sheer coincidence, some of the prominent writers of Malayalam fiction of that era were all then based in New Delhi. The weekly sessions of the Delhi writers at the Kerala Club, in which Sethu was a regular member, emboldened him to start writing. It was the period when the wave of ‘modernism’ was sweeping across Malayalam fiction and these writers were always willing to explore new vistas of human experience and experiment boldly with the form and content alike. Their narrative styles were totally different from that of the earlier generation of realists and romanticists. Some of the significant works of this generation, which were of a distinct class altogether, were so compelling that it generated a sense of creative participation between and writers and readers at the sensibility level, transforming the overall quality of reading and writing alike.

Interestingly, Sethu’s first story, Dahikkunna Bhoomi, which appeared in the Mathrubhumi Weekly in 1967, was not on Kerala life. Its backdrop was the severe drought the villages of Bihar had experienced during the mid-sixties. Thereafter, he has written a number of stories, many of which have been translated into other Indian languages. His much acclaimed novel Pandavapuram, has been translated into English, German, French, Turkish, Hindi, Marathi, Tamil, Kannada, Telugu, Bengali and Oriya. Niyogam was published in English(The Wind from the Hills) and Atayalangal in English, Hindi, Tamil, Telugu and Kannada. Aramathe Penkutty has come out in English, Hindi, Tamil and Telugu. A movie Jalasamadhi based on his story and scripted by him was exhibited in many international film festivals. Another film Bhoopatathil Illatha Oridam, based on his story was also made in Malayalam. A TV series called Sethuvinte Kathakal, comprising of 17 stories was telecast by Doordarshan. A film based on Pandavapuram was also made in Bengali under the name Nirakar Chhaya by Ashish Avikuntak.

He was the Chairman of National Book Trust India, New Delhi from 2012 to 2015. A Fellow of the Kerala Sahitya Akademy, he was also in the General Council of the Kendra Sahitya Akademi and Executive Committee of the Kerala Sahitya Academy.