To explain Fal’s choice I need to explain a bit of backstory. Fal’therin has been a ranger of Quel’thalas for nearly three thousand years. It’s his life. He doesn’t know anything else. He’s an old, experienced soldier who’s dedicated his life to protecting the forests, and the Kingdom of Quel’thalas.
In recent years, that protection took on a darker aspect. Without the Sunwell, Fal’therin put tactics over ethics, if you will. Yes, fel was life draining - an antithesis to the life he protected. But it was necessary to PRESERVE life, and so he consumed it to feed his magic addiction, like most Blood Elves. Fearing that the Sunwell was vulnerable after the damage it caused after Arthas corrupted it, Fal’therin was always skeptical after its restoration. Fel, while more volatile and dangerous, was in a way less vulnerable. Destroy a fel crystal and you destroy one of many sources of magic - and the elves simply get a new one. Destroy the Sunwell and you doom an entire race. So Fal kept seeking for new powers that could not be easily destroyed, thus granting independence from the Sunwell, which led him down the road of becoming a void elf. Here we are today.
Fal delved into the Void because he felt it could be used to protect Quel’thalas. He felt that the Grand Magister would see it as useful, not something to be reviled, if he could truly see what it could do. Fel was once considered too dangerous to wield, after all, and it saved the Blood Elven race for a time.
Anyway, so here we are today and Fal’s kinda lost his life’s purpose. Delving into the void, he believed, was a strategic move. One that has its uses but largely failed miserably. He didn’t intend to be exiled from the home he spent millennia trying to protect… but here he is. Now he’s a bit lost.
The Night Fae, for him, are somewhat grounding in a way. It’s this pristine forest. All about life, renewal, rebirth. About spending an eternity in the forest, after a long and hard life, as an animal in the forest, wild and free. He’d become a Dragonhawk if he could.
But I can see Fal seeing this as his ideal afterlife. It’s not the forest he spent his life protecting… but it’s a beautiful one with a reason to fight for. In a way Fal’s fallen far from being the nature-protecting Ranger of the old days. Now he wields fel and void and fights more for politics than for the simple beauty of the forests, of life, that he once wanted to protect.
I think the Night Fae will remind him of what he’s missed. There’s an innocence in those forests, a peace, that he’s really been lacking. I think he sorely needs it. And so Fal’therin, my Void Elf Ranger, is going Night Fae.