"It was just a simple spell. Actually, no. It wasn't. But no one, not even Celestia herself, could have predicted this outcome. Well... Maybe Celestia could've seen it coming. She's a god, and all that jazz. Now I'm stuck, for some time, in a land that's so much like my own, but still so different. So very different."
Twilight's magical experiments are commonplace enough, but she's refrained from testing on living things for several reasons. When she finds herself with a spell that only works on the living, she's faced with a conundrum. Luckily, she has a cadre of people who'd be willing to volunteer. And, from that cadre, she picks a very significant other. Now, subjected to a spell that does more than he could've predicted, Icarus is forced to see the world in a vastly different light.
Sometimes it's the small things in life that matter the most. Other times its the not so small things. At the end of the day, though, the most important things are the ones that we choose.
Twilight's experiments take a rather unexpected turn for Icarus, who soon finds himself in a situation where he is forced to decide what he really sees when he looks at the members of his herd.