@john92  
I would think that a conbination of the constant pressure put on by being a good assistant and the fact that he is basically the Mane Six’s (Seven now) punching bag would be good enough, however maybe an old villain would be able push him that bit further by suggesting manipulating Spike a bit more?

@TheAbridgenator  
I’ve been around for a long, long year…  
Stole many a man’s soul to waste

@john92  
As has become a mantra among Spike fans, “the series is Spike’s villain origin story.”
 
Go ahead, Twilight, roll your eyes at him and laugh at him some more… let’s see what happens.

This is one sexy ass Spike, gotta say. :v

I would actually like to see Spike become a villain. A corrupted older spike gives Twilight a choice, She has to use the elements of harmony to turn him into stone/banish him. If she doesn’t he will go on a rampage and burn Ponyville to the ground. He knows that Twi will never hurt him leaving him to do as he pleases. It will also show Twilight as a weak leader and not fit to rule, which makes the citizens of Equestria turn on her and adds more stress to her situation. All he would need is some motive to turn evil.  
What do you guys think? Would you like to see Spike turn heel? What would be his motivation? What situation would you put him? I want to hear your opinion on this matter.

He looks like a Roman Emperor.

he actually looks quite charming, I wonder if he’s in a relationship, since he probably couldn’t care less about Rarity at this point.

A fitting punishment for the Crystal Empire.

@CogWeaver  
Please allow Spike to introduce himself, he’s a drake of wealth and taste…

@SquiggyBomb  
That’s probably the trick right there.  
An evil looking dragon would immediately put you on guard, whereas a kind, even handsome looking dragon could sidle up to you, greet you pleasantly, offer you some form of hospitality, and then bite your head off.

See, I think the necklace should consist of five gems, with Twilight being the centermost one. Why five, you ask?
 
Simple. One word: Rarity.
 
She has been the defining focus of Spike’s greed and lust, and her influence has caused him to do very drastic and insane things for her. If Sombra’s dark magic augmented his greed enough that he would betray his teacher, I do not doubt for a second it could corrupt his desire for Rarity into something monstrous and ravenous. For him, the other four ponies were window dressing and Twilight was a source of much frustration, but Rarity was always viewed as special and unique by Spike, so I imagine she’d be given a unique punishment, or perhaps a reward from his perspective. He’d likely make her his chief concubine or “queen”, and subject her to his dark arts now that she has literally noone to defend her.
 
After all, if you had the Holy Grail, would you set it with the rest of the “good china”? Or would you set it on an alter, locked away from anyone else who could defile it?
 
Anyway, pardon my ramble. Awesome work!

Okay, I know he’s supposed to be evil.  
But did you have to make him so bloody HANDSOME?!