Big Macintosh was a simple apple farmer pony, but once he's imprisoned under false charges for sexual favors, he receives a package in his cell containing means for his escape, and a letter that would change the way he saw the world forever.
Despite herself, Twilight starts to think that Rainbow Dash might be right about Rarity having a crush on Big McIntosh. And, well, friends help friends out in situations like this, don't they?
Spike & Big Mac have gotten pretty close over the years, bonding while the girls were off saving the world. They finally admit their feelings for one another, as soon as Spike comes of age, but they hit a snag in their relationship. A BIG one.