Awhile ago, I wrote a one-shot based on something I found on Tumblr. The back story wouldn't leave me alone, though. This past February, one of the pages I follow had "Loki Month", which had different prompts for different times of the month. One of the prompts was AU (Alternate Universe). This fit my one-shot perfectly, and I was able to write out the complete story of Loki and Sarah.
In this universe, Loki was told that he was adopted and the child of Laufey. As a result, his upbringing was much different from the God of Mischief we all know. Once Thor became King of Asgard, Loki grew bored and traveled through the Realms. While on Earth, he met and fell in love with Sarah. They married, had an adorable daughter, and lived on Asgard.
Now, part three is pretty much the one-shot that I'd written, however, I have added a bit more for the purpose of this story.
UPDATE 2/28/14: Ok, there was originally only going to be three parts, but it looks like there will be four now. The fourth part with include bits of the one-shot that were supposed to go in part three.