Fowler because in the story it is given that Fowler went to meet Ausable as a guest.

Guest in the Story 'The Midnight Visitor'
The guest in the story 'The Midnight Visitor' is Mr. Oliver. He is a man who arrives unexpectedly at the narrator's house in the middle of the night, seeking shelter from the storm outside.

Appearance and Behavior
Mr. Oliver is described as a tall, thin man with a pale face and dark eyes. He is dressed in tattered clothing and appears to be quite nervous and agitated. Despite his unkempt appearance, he speaks politely and gratefully to the narrator, expressing his gratitude for being allowed into the house.

Reason for Visit
Mr. Oliver explains to the narrator that he had been traveling through the countryside when the storm suddenly hit, forcing him to seek refuge. He appears to be in a hurry and seems anxious to leave as soon as the weather clears up.

Suspicious Behavior
Despite his seemingly innocent appearance, Mr. Oliver's behavior raises suspicions in the narrator's mind. He is caught snooping around the house late at night, which leads the narrator to believe that he may have ulterior motives for his visit.

Resolution
In the end, it is revealed that Mr. Oliver is actually a criminal who had escaped from prison and was on the run from the authorities. The narrator confronts him about his true identity, leading to a tense confrontation before Mr. Oliver flees into the night.
Overall, the character of Mr. Oliver serves as a mysterious and intriguing figure in the story, adding an element of suspense and danger to the narrative.