It's a little rushed, but I like it :) Add a bit more sensory detail, and it should make it a bit longer.

An alien sent her to destroy Earth. Cool!

It was a good cliffhanger:) I like the premise and Nikki's mysterious step mom is interesting as is his own Dad. There were parts that seemed somewhat rushed but just taking the time to develop your characters and story should remedy that. I'll check out your other story as well:)