I have a lot to say about this!!
Ok, here it goes (please, be patient with my english... I'm still learning ^^ )
Spike, at the moment, have bad chances. Why?
Age is the main problem. I mean, how old is he? 12? 13? Yes, he can actually grow up in a day, but... I don't know. He's still a boy. Maybe in some years, age won't be a problem; Rarity can't be more than 18-19 years old, at least in my mind (she's younger than Applejack and maybe Fluttershy). In ten years, Rarity will be 29 and Spike 23. That's ok for me. Imagine that, maybe, he is not that young. Maybe dragons are adults when they are about 2-3 (because of greed). But they are adults at that age. Spike mind is not too far from the main 6, in some situacions he's even more mature than some of them. In some, he really looks like a kid.
Dragon-Pony is fine! I mean, I've seen LOTS of similar examples (Roger Rabbits, for example, the Dragon and Donkey... and even more if I think a little), and I don't see this as a problem.
Rarity: She thinks about him as a child. She looked maternal for me in Dragon Quest, not in love. But their relashionship is better now, yes. She wasn't so kind with him before. She was really worry for him, even more than Twilight! At the end A Canterlot Wedding, she wasn't dancing with him.
And that's what I'm afraid of. Spike was dancing with Sweetiebelle. Ugh. I didn't like that!
I do believe that, since most of the fans like this couple, writers will find some way of giving us a smile. They really look up to fans, and that's giving me hope. I read that he's an underdog. He is, and in most of the times underdogs win.
If writers want Sparity, they will find a way. It's curious, in some way, that they have so many things in common!
- Love gems.
- Generosity - Greed
- Idea of romance
- Both are smart
- Both have class (Spike lived most of his life in Canterlot!)
I want to see if this continues on season 3.