It was Sigismund Dijkstra
Although he introduced himself as Sigi Reuven
'The world has changed,' said the pilgrim. 'Something ends. I'm Sigi Reuven.'
Djikstra was the head of Redania's intelligence and at some stage a de-facto ruler of Redania. This was making him too powerful in the eyes of the nobility, hence a team of assassins was sent to imprison him. Fortunately for him, his past affair with Philippa Eilhart allowed him to escape using a magical portal. To honor his long-time assistant Ori, he has taken his surname:
'Good evening, ahem, ahem, my lord...'
'Shadow People,' Dijkstra read the front of the manuscript that he had taken from the table. 'Or the story of His Majesty's Secret Service, written by Oribasius Giafranco Paolo Reuven, law grad... Oh, Ori. At your age, such nonsense...'
'Ahem, ahem...'
'I came to say goodbye, Ori.'
Reuven looked at him in amazement.
'You see, my faithful friend,' said the spy, without waiting for the clerk to cough, 'I am old, and besides that, I am stupid. I said a word to one person. Only one. And only one word. It was one word too many, and one person too many. Pay attention, Ori. Do you hear?'
Ori Reuven rolled his astonished eyes and shook his head. Dijkstra was silent for amoment.
'You do not hear,' he said after a moment. 'And I hear them. In the corridors. Rats running around the city of Tretogor. Here we have them. Approaching on their soft little paws.'