Spike has been secretly admired for a few months now. One day, this admirer decides to reveal their presence in the form of clues. Spike decides to follow the clues, and soon discovers that his secret admirer is somepony that he didn't think even existed.

Spike x SlenderMane (or in this case SlenderMare)
and possibly another mare??

I got the idea to write this from reading DARKPHANTOM13's story Spike's Stalker.

Note: Spike is 18 in this. And this story happens shortly after the season 4 episode "Princess Twilight Sparkle."