The Question and Answer section for Frankenstein is a great resource to ask questions, find answers, and discuss the novel.
The thunderstorm and the destruction of the tree was Victor's first experience with electricity. Although Victor had previously been exposed to electricity, this is the incident that sparked his real interest.
When I was about fifteen years old we...
The creature says that Victor owes him a companion because he was created and abandoned. He wants someone to be with, and he doesn't want to feel the lonliness thrust upon him. He wants Victor to make a female monster for him.
This all depends on what point in the story are you referring to.