After reaching Ponyville, Blade and Frost would have found places to stay, and perhaps work. Locals explain to them that the Summer Sun Celebration was tomorrow, and they would attend.
When Nightmare Moon appears, the Mane Six go after her, but the situation in Ponyville degrades into chaos. Blade and Frost try to calm people, and fend off monsters, such as the dragon seen in chapter 3.
When Celestia returns, all is peaceful again. Blade and Frost, having worked together to stop monsters (because they had nothing to lose), become acquainted.
And that's the story.
And yes, later in the series, I would ship them.