In the first opening paragraph of the novel, readers are introduced to Lockwood, an unreliable narrator who tries to make sense of his surroundings and his landlord. Comment on this.

Lockwood brings his own assumptions about how people should behave and projects them onto Heathcliff and the other occupants of Wuthering Heights. Lockwood is a cheerful, silly, friendly man and expects to find a cheerful reception in this lonely spot. He first decides Heathcliff is a "capital" fellow and jumps to the conclusion that his landlord will be a good companion. As he finds out soon enough, he couldn't have been more wrong.
He is right that he has come to a beautiful countryside, but he is in error when he thinks this about Heathcliff in the opening paragraph:

Mr. Heathcliff and I are such a suitable pair to divide the desolation between us.

Lockwood, as later paragraphs will show, has, unbeknownst to himself, stumbled into a severely dysfunctional family situation. In the first paragraph, he evaluates his situation incorrectly. He is in way over his head. He and Heathcliff are not in any way a suitable pair. This is not his pleasant, easy, superficial world where people are polite to one another. He is initially attracted to the pretty young Cathy, but she is ill-mannered and angry.
Lockwood later finds, to his surprise, that Heathcliff is not a kind or pleasant fellow. When Lockwood gets trapped at Wuthering Heights, where he comes to visit though he was not wanted in the first place, he gets even more deeply mired in the family drama. He sleeps in Catherine Earnshaw's old bedroom in her old bed, and he either dreams of her or encounters her ghost as it tries to get into the window. Lockwood's crying out in the night deeply upsets Heathcliff and whets Lockwood's appetite to learn more of this family backstory. He is a completely clueless person, but because of him, we get to hear the dramatic saga of the Earnshaws and Lintons. He is a foil to the Eanshaws, highlighting how fierce and rugged they are, in contrast to a pampered high-society figure like him.