The main character in 'Cawnpore' is fictitious, but many of the others were real people. The most significant is Nana Sahib.
Seereek Dhoondoo Punth, generally known to the British as Nana Sahib, was seen by many Victorians as an evil plotter, who lulled the British into a false sense of security in order to betray them and commit what many would see as the most appalling act of the Mutiny. In fact, he was a more complex character than that.
He came from an undistinguished family but was adopted by Baji Rao, the Peshwa of the Maratha Empire. Although the title of Peshwa originally referred to the Chief Minister, who would serve for eight or nine years, by the time of Baji Rao the position had become the hereditary ruler of the Empire. His capital was at Poona (now Pune), which was one of the main political centres of India. From there, he ruled over the most important of the Indian kingdoms.
The Maratha Empire was riven by internal strife and some factions went to war against the British. There were three wars in total and, after the third, the British decided to annex the Maratha Empire. Baji Rao was allowed to keep his title and even given a pension by the British. However, he was stripped of all political power and forced into exile. He chose to live in Bithur (now Bithoor), a small town near Cawnpore.
Baji Rao needed a male heir to succeed him and, in the absence of a natural heir, Nana Sahib was adopted in 1827 and raised to inherit his father's position. The British, however, refused to acknowledge that an adopted son could inherit a hereditary title and would not acknowledge him as Peshwa. By then, the title was purely honorary and it is possible that the British did not realise how much distress this caused, although Nana Sahib petitioned repeatedly for his title to be recognised. He also petitioned that the pension that was paid to his father should continue to be paid to his father's heirs, but the British refused to do this, claiming that the pension had been personal to Baji Rao and their obligation had died with him.
Nana Sahib toyed with the idea of travelling to England to appeal directly to the East India Company but, as a Brahmin, he would have lost caste by travelling overseas. He therefore sent Azimullah Khan, one of his most trusted advisers. Azimullah Khan appears to have enjoyed his trip, especially as he was something of a ladies' man and was a great success with many of the women he met in London. However, he was completely unsuccessful in pleading Nana Sahib's cause and the experience seems to have left him with a very strong antipathy for the British. During the events at Cawnpore, he constantly advised Nana Sahib to act against the Europeans.
Nana Sahib does not seem to have been a very strong character. He sought to curry favour with the British and was seen as a good friend until the Mutiny. Even then, the British allowed him to guard their Treasury, thinking he might prove loyal. With British power under attack, though, many of his advisers, especially Azimullah Khan, urged him to act decisively against the occupiers, and regain his rights and titles through military power. It seems likely that Nana Sahib vacillated between these two positions, partly because he was not sure who would come out on top and he was anxious to be on the winning side. Eventually, though, he was convinced to throw in his lot with the rebels. It is likely that he was then pressured to agree to the treachery and the massacre in order to prove that he was firmly on the side of the native population and that he would not be able to turn against them if (as happened) the British returned to Cawnpore in force.
Despite his initial wavering and his military incompetence (the British should have been driven out within days), Nana Sahib eventually became a more decisive leader. In fact, after Cawnpore was recaptured by the British, he led another attack on their positions, and continued to harry their forces for some time. Eventually his armies were defeated and he fled. He was never captured and his final fate is unknown.