Due to their cold nature, the tree of life gradually withered. The elves have not had any new elves for hundreds of years. As the elves gradually disappeared and headed to the pure land, they had to pray to the goddess of nature to regain their lives.
So the goddess of nature gave Linna a new life with Leinster, the son of the lord.
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The female protagonist travels through time because of the elves' prayers, and the male protagonist is the elves.
Brainless sweet article, one of my jokes, if it's not sweet, it doesn't cost money. Some settings are borrowed from The Lord of the Rings. If there are any similarities, I borrowed from him [not much, because it is essentially a female novel, Brother Jade's consistent style].
Concept: Elf male protagonist x female protagonist