It was China’s decision to jail Liu Xiaobo for 11 years over a call for peaceful democratic reform that spurred the Norwegian Nobel committee to honour him with its peace prize in 2010 and propelled him to international renown. But his first nomination had come two decades earlier, after the Tiananmen Square pro-democracy protests of 1989, in which the author and intellectual played a key role, first as one of the prominent “four gentlemen” who launched a hunger strike in support of the students; then by helping to broker a peaceful exit from the square for remaining demonstrators amid the bloody crackdown.

The events were the turning point in Liu’s life. The writer, who has died aged 61 of cancer, was abroad when the movement erupted and he went home despite the risks. It brought jail, an end to his career as a brilliant young literary professor, and the ending of his first marriage to Tao Li; thereafter his contact with his son, Liu Tao, was limited. But the transformation was internal too. He never forgave himself for writing the confession that shortened his sentence. He believed he had not only sold out his dignity, but also the souls of the dead.

After 1989, many outspoken figures fled abroad or fell silent: “Others can stop. I can’t,” said Liu, believing that to abandon course would be a second betrayal. He dedicated his Nobel prize to the martyrs of Tiananmen Square.

Liu was born in Changchun, Jilin, in north-east China, into an intellectual family. His parents, Liu Ling and Zhang Suqin, were devoted to the party, but from his youth Liu struck an independent course. After studying Chinese literature at Jilin University, he began an MA in 1982 at Beijing Normal University, where he stayed on as a lecturer. His keen intelligence and razor tongue soon established his reputation: hundreds watched his dissertation defence, while students from other universities packed out his electrifying lectures. He was also a visiting lecturer at the universities of Oslo and Hawaii, and Columbia University in New York.

He made as many enemies as admirers in those years. He was as merciless in dissecting friends and apparent allies as political opponents. He was individualist to the core, his friend and biographer Yu Jie noted, and it cost him close friendships. Later on, he acknowledged that he had been preoccupied with ideals of justice and human rights, showing little concern for the people around him. While he let some down he was steadfast in his commitment to others, becoming especially close to Ding Zilin and Jiang Peikun, who had founded the Tiananmen Mothers pressure group in response to the killing of their 17-year-old son.

Friends noted that he was far less abrasive in maturity and, as co-founder and director of the Independent Chinese PEN centre, showed an unexpected talent for dialogue and compromise.

In 2008 he helped to draft and gather support for Charter 08, a bold call for peaceful political reform and an end to one-party rule, inspired by the Czechoslovakian dissidents who issued Charter 77 in 1977. Police detained him at his flat two days before its release and the following year he was given a punitive 11-year sentence for inciting subversion. He was adamant that this time no confession would shorten his sentence.

China censored discussion of Liu and his Nobel win domestically. But intermittently its media denigrated him as a shill for western governments, highlighting his support for the Iraq war and a remark in a 1980s interview that it would take “300 years of colonialism” for China to reach Hong Kong’s level of development. Such comments were never contextualised, and though Liu saw western civilisation as a tool that was useful to reform China, he said it was utterly flawed and in need of critique itself. In any case, those comments bore no relation to his jailing.

Despite Liu’s sometimes acid remarks he was anything but austere; and was warm and playful with those he knew well – one letter to a fellow dissident, a serious discussion of political resistance, begins “Dear Baldie, or is it Beardie?”. He relished good red wine until hepatitis stopped him drinking. Friends teased him about his love of good food and voracious appetite, which he ascribed to the devastating famine of his youth, as well as to being one of five sons.

But even when notionally free, his life was shadowed by harassment, questioning, house arrest and surveillance. Asked why he continued – and why he made ambitious calls for fundamental reforms instead of targeting incremental improvements – he said his role was to push for changes that would benefit everyone.

It was in a labour camp, in 1996, that he married the poet Liu Xia. Her devotion sustained him and – painfully aware of his shortcomings in his first marriage – he was a very different husband the second time around. He took enormous pride in his wife’s talents.

“Your love has been the sunlight that leaps over high walls and shines through iron bars,” he said in a statement at his trial in 2009. “My love for you … is so full of remorse and regret that it at times makes me stagger under its weight.”

They were planning for their life after his release. But late last month it emerged that Liu Xiaobo had been diagnosed with late-stage liver cancer, and he was transferred from prison to hospital, still under heavy guard.

“A calm and steady mind can look at a steel gate and see a road to freedom,” Liu once wrote of life as a prisoner. The gate remained locked and outside the political repression increased. Friends were bitter at the strikingly late diagnosis and the authorities’ refusal to let the couple go abroad or release them fully. Yet the man who alienated so many in his youth had told his trial that he had no enemies, speaking kindly of the police, prosecutors and judges.

He insisted that love could dissipate hate, and that progress would be made. No Enemies, No Hatred, a selection of his essays and poems, was published in 2013.

Liu is survived by Liu Xia, who has been living under house arrest since 2010, and by Liu Tao.

• Liu Xiaobo, author and Nobel peace laureate, born 28 December 1955; died 13 July 2017