Spike is Twilight Sparkle's pet, and a Dragon. In my opinion, this is how Spike is.
Spike is *Cough cough* Unnecessary. Suprised? Well, he's only comedy, and doesn't do anything with the plot. The only thing where Spike actually does something important is when he saves the Crystal Empire? I think it's called that.
But, still, they could have easily made Twilight save it anyway, but they needed to get Spike some attention... Sorry for you Spike fans. It's just true. Think about it.
Also, he makes a bunch of bad things happen. He went out on the dragon migration, practically forces the ponies to go, (since ya know, he's definitely gonna get hurt err... Beat up) and then almost get them killed by dragons. But, oh, he got the phoenix egg, so every things alright. And they talk about the egg for a few episodes and its gone..
That's just my opinion. Don't freak out.