From the longer story description and the tags, without having read it yet, I would expect...
The sisters are barren, but Spike can impregnate them with his magic cum because he's a dragon. But not only them, he'll also make a harem out of the Mane Six, maybe the dragon girls we know, probably Gabby, and the CMC. Flurry, maybe, if she's old enough. Essentially, all the girls, which makes me hope this Equestria has a ludicrous female-to-male ratio or Spike collecting literally every desirable female in the world like Pokemon feels a little unfair to everyone else, who wasn't born a super-special dragon.^^
There might be a cabal of Racist Unicorn Nobles (it's always Racist Unicorn Nobles, can't remember the time it was either not a Unicorn or not a noble) as well who wish to exile and/or kill Spike for not being a Unicorn, which is totally unfair even if Spike once almost destroyed Ponyville through dragon greed-growth, which is probably not going to be brought up. The chances of this are much higher if it's a "Prince Spike" scenario.
How am I doing so far?
And sorry if this comes across as a little aggressive. It's not meant to be, honestly, it's more that I've seen similar setups before and some things tend to become rote after a while. Who knows, I might be completely off, and if that's the case, I will freely admit that I was. Don't let me discourage you. And if you do want to talk about things, I'm actually fairly approachable.
From the longer story description and the tags, without having read it yet, I would expect...
The sisters are barren, but Spike can impregnate them with his magic cum because he's a dragon. But not only them, he'll also make a harem out of the Mane Six, maybe the dragon girls we know, probably Gabby, and the CMC. Flurry, maybe, if she's old enough. Essentially, all the girls, which makes me hope this Equestria has a ludicrous female-to-male ratio or Spike collecting literally every desirable female in the world like Pokemon feels a little unfair to everyone else, who wasn't born a super-special dragon.^^
There might be a cabal of Racist Unicorn Nobles (it's always Racist Unicorn Nobles, can't remember the time it was either not a Unicorn or not a noble) as well who wish to exile and/or kill Spike for not being a Unicorn, which is totally unfair even if Spike once almost destroyed Ponyville through dragon greed-growth, which is probably not going to be brought up. The chances of this are much higher if it's a "Prince Spike" scenario.
How am I doing so far?
And sorry if this comes across as a little aggressive. It's not meant to be, honestly, it's more that I've seen similar setups before and some things tend to become rote after a while. Who knows, I might be completely off, and if that's the case, I will freely admit that I was. Don't let me discourage you. And if you do want to talk about things, I'm actually fairly approachable.