I assume you are asking about Lockwood's first encounter with Heathcliff when he visits Wuthering Heights at the beginning of the novel. When Lockwood first arrives at Wuthering Heights, he finds the property to be just an inhospitable as the residents. Heathcliff is especially gruff and impolite. When Lockwood asks to stay the night, Heathcliff says he has no place for visitors and refuses to allow Hareton to accompany him at least part of the way back to the Grange. However, once Zilah rescues Lockwood and lets him spend the night in Catherine's old room, Lockwood discovers Catherine's old diaries. As Lockwood reads the diaries, he, as well as the audience, begin to see Heathcliff in a different way. Lockwood reads about Heathcliff's mistreatment as a child. After the ghost incident, Heathcliff cries loudly, obviously still desiring Catherine. Lockwood can see that Heathcliff has suffered tremendous losses and poor treatment from others. This allows Lockwood, and the audience, to begin to have sympathy for Heathcliff. By the time Lockwood leaves Wuthering Heights, he sees Heathcliff in a much more sympathetic manner than he did at the beginning of his visit. In fact, Lockwood is so intrigued, that when he returns home to Thrushcross Grange, he asks Nelly to tell Heathcliff's story. Thus, Lockwood's visit serves as the motivating force behind the telling of the entire novel.