At the beginning of the series, Leshawna held a grudge against Harold for calling her really big and really loud, to which Leshawna responds by yelling at him. But over time Harold developed feelings for Leshawna and started sending her love letters. On the episode that Harold got voted off, he revealed that he was the one who was writing Leshawna love letters, much to the girls' surprise, then Leshawna ran over to Harold and hugged him before giving him a passionate kiss, earning a gasp and an "awwww" from all the girls.
In the after episodes when Leshawna and Harold were hanging out at Casa De Losers, Leshawna told Harold that she never meant to lead him on, and that she only kissed him because things were all emotional. This doesn't register in Harold's brain, and he still believes that they're going out. He even says in the confessional that Leshawna might move in with him after the show.
In the second season, Leshawna was voted off before Harold was. As she's getting in the lamozine, Harold runs after her and sobs, telling her that the guys told him to vote her off because he didn't know if he could trust her. She simply smiled and patted his head, telling him it was alright, and that he should stick up for himself from now on since she won't be there to do it for him. She then faces Heather and admits that she can call Heather her friend and that they were friends for a long time. Heather then smiled and said, "Thanks." Then Leshawna got in the lamozine and rode off.