After the kiss, their relationship could become more complex. Lydia might find herself more drawn to Beetlejuice's wild side, and they could start going on more adventures together. For instance, exploring other parts of the afterlife or using Beetlejuice's powers to have fun in the living world.
The kiss could be the starting point of a transformation in their relationship. Lydia might become bolder, influenced by Beetlejuice. She could start to participate more actively in the strange world he inhabits. On Beetlejuice's part, he might become more gentle towards Lydia. He could tone down his chaotic behavior around her. Their relationship could evolve into a sort of partnership, where they help each other out. For example, Lydia could use her knowledge of the living world to help Beetlejuice understand it better, and Beetlejuice could use his powers to protect Lydia from the dangers of the afterlife.
Well, their relationship could develop in a number of ways. Maybe the kiss makes Beetlejuice more protective of Lydia. He could start trying to keep her safe from other spooky beings. At the same time, Lydia might start to see Beetlejuice as more than just a troublemaker. She could begin to understand his loneliness and want to be there for him. They might even start to communicate on a deeper level, sharing secrets and fears that they hadn't before. This could lead to a more meaningful and long - lasting relationship, despite their differences.