Why even have Steven?

Aside from the fact that Steven is the titular character, I can't help but wonder; why even have Steven? I mean, it cost Rose her physical form, which devastated Greg and the Crystal Gems. She obviously knew it would cost her form and so obviously she'd talked to Greg about it...so why would he go through with it if it meant it would cost him Rose?

Also don't get me wrong, I love that cutie Steven. This is just curiosity's sake.

I think that Rose Quartz anticipated that, if the Homeworld ever returns, they need to have something that the Homeworld didn't anticipate: a half-human half-gem.

In Jailbreak, because of Steven's partial humanity, he is basically immune to the Gem Destabilizer, and cannot be held in the prison.

She also might have anticipated that other humans, since Greg got involved in the minimal ways he was, might want to join them for the cause. A half-human half-gem like Steven might be more capable of attracting humans to the cause.

If "We Need to Talk" involves a Rose/Greg fusion, Rose might come to the conclusion that a human could fuse better with a half-human half-gem. "Alone Together" has Stevonnie, a stable fusion between Steven and Connie.

I think Rose needed to find a human that she romantically loved enough to carry the child of, at the right time, and Greg was the lucky guy at the right time.

I have to go with winduko. Steven adds a different element that the gems don't have. Him being half human has proven to be helpful.

So...like a battle tactic?

Yeah.

Steven's primary existence is to be an advantage over the Homeworld. I have no doubts that Rose loves Steven, but Rose felt that Steven needed to be here, fighting in her place.

I wouldn't say he was JUST a battle-tactic to her. I'm sure a big part of her having Steven was because she wanted to know the feeling of being a mother. And I'm sure she wanted Greg to have the opportunity to have kids as well.

But I do agree that she probably had some other motive for giving her life to have him. He is a great bridge between the Gems and the humans.

I think her main reasoning was to give Greg the kid he never would have had if she had stayed but I think the benefit he would have being half human-half Gem was what made her decision final.