This story is a sequel to Fireflies

"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.