We’ve finally got an answer to one question: yes, Steven can shapeshift to modify his form. While we’ve learned about shapeshifting’s energy drain though, it leaves us wondering about the mechanics of this seemingly universal feature of gemkind.
In Log Date 7 15 2 Peridot comments on Amethyst’s frequent use of shapeshifting, saying that it is a significant use of energy compared to the benefits of the uses Amethyst has for it. This short sentence is a source of a whole mess of speculation about one big question: do the Gems have a set “energy budget” for their lifespan?
At first it would seem like the most probable answer was “yes”, since there’s no real point to mentioning it if the gem is constantly generating new energy to use with no concern for fuel. This would have unpleasant implications for Amethyst and the universe: Amethyst would be frivolously shortening her life, and the Gems will eventually leave the universe a barren husk without even surviving Gems to show for the use of the kindergartens.
However upon consideration we don’t think that this is the case. First of all, Peridot doesn’t seem to consider the waste of energy to be something to be concerned about. As a certified technician she likely has a bent towards efficiency, which might cause her to mention it, but if she were aware that there was no real downside then she wouldn’t be worried about it either.
Life and death on the planet Earth
Second, the damage the kindergarten does to the surrounding area is permanent: nature reclaimed the strawberry battlefield quite handily, but even after thousands of years there is still a sharp, zig-zagging dividing line between the black, dead ground surrounding the kindergarten and the verdant wilderness beyond.
If there is no way for the Earth to replenish this “life force” that the kindergarten siphons, then assuming it isn’t scheduled to run out of it on its own either we have an explanation for how a Gem’s gem could keep her powered indefinitely without making physics too angry: while we’ve just introduced an infinite power source to the universe, it’s normally put to use sustaining life (and in a way, the Gems continue to use it for that very purpose). We hope physics understands.
Ready for battle!
So assuming that we get an infinitely long-lived Gem (until shattered, anyway) out of siphoning a planet’s life force, why the concern about the energy expenditure? Reformed may have the answer. As we saw then, Amethyst was able to briefly squeeze some extra power out of her gem before her new form started to fail (presumably from over-consumption of energy). Obviously there is some buffer of extra energy, allowing a Gem to call on it faster than her gem can recharge it. Shapeshifting might dig into this buffer, meaning that were more drill parasites (or some other monster) to pop up out of the ground and attack the next time Amethyst tries to lion the mood, she won’t be completely ready for the fight because of her shapeshifting’s power consumption.
Amethyst’s warning to Steven that staying stretched out can hurt him also agrees with this: the energy consumption is fine for a while, but if carried on so long that the buffer is exhausted, bad things can happen.