Perhaps the man felt it was time to tell his story and Walton happened to be there. Or maybe he thought his story could have some sort of impact or lesson for Walton.
It could be that he saw something in Walton that made him trust him enough to open up. Maybe Walton showed genuine interest or empathy.
Maybe he just wants to share his experiences and get something off his chest.
Maybe he wants to share his experiences and feelings with others.
Walton is a fitting man to tell the story because he has a curious and observant nature that allows him to capture the details and emotions effectively.
Maybe he's a kind person and wants to help Walter. Or he could see some benefit for himself in doing it.
Maybe he was persuaded by Walter's passion and the importance of the story.
Perhaps he wants to share his experiences as a form of catharsis. Telling his story could be a way for him to unload all the pent - up emotions and memories related to his homelessness. It could also be a way for him to make sense of his own life and situation.
The length of time Victor Frankenstein spends telling his story to Walton is quite substantial. It seems to go on for days or perhaps weeks, as he recounts his complex and disturbing experiences in detail.
Walton's duty might be to listen attentively and document the story accurately to share it with others.
Perhaps Walton's duty is to act as a confidant, showing empathy and helping the man express his thoughts and feelings fully. Also, he might have the responsibility of preserving the story and sharing it with others if necessary.
He might tell his story to share his experiences with others.