Magvel love

Did Lyon know what would happen to his soul? Or rather; did he sell his soul to the Demon King in order to receive whatever he wanted (confidence, strength, respect and one of the twins, I believe)?

I don't believe there is anything in canon that hints at one of them, does it? And it would change many things, wouldn't it? Well, maybe Lyon didn't completely know what it means to sell one´s soul (and by that I don't mean the technical stuff, but the real life consequences and changed feelings and everything. Words and explanations can never fully describe reality).

Related to that question; 

Ephraim´s route:

Lyon:
Then I acquired the Dark Stone. The Demon King began to eat my soul and corrupt my flesh. I almost vanished beneath the Demon King's mantle. Then I remembered you [Ephraim]... My mind blazed into wakefulness. All at once, my mind shouted out, "I will not be devoured!" Just as I was about to lose myself to the Demon King. I was able to drive him back. The Demon King's desires are simple--foul, but uncomplicated. He wants nothing but the destruction, conquest, and subjugation of man. These shallow desires are nothing to the dreams of the human heart. And of the two roads I had seen, I chose the latter.

Eirika´s route:

Evil Lyon:
I'm afraid there's no hope of that. You see, I've devoured him [Lyon]. Bite by bite, slowly. How I savoured it. Nothing remains but this suit of flesh I wear. There is nothing to heal. Not even the power of a Sacred Stone can craft something from nothing. He cannot be saved.

Which one do you think is closer to the truth? Has Lyon any chance to resist the DK? Or is the DK just using "Lyon" to mock and weaken Ephraim? How much Lyon is left? (Yes, this is partly headcanon time~)