Power complications

Kara was just starting out as Supergirl. Her friend Winn had helped design her costume, through much embarrassing trial and error (just the idea of going outside in the first shockingly skimpy thing he proposed made her flush), and now finally she could be a hero just like her cousin was.

Ok, her first night out hadn’t gone spectacularly; the DEO had found her, though she’d relatively quickly decided to help them. They fought aliens, they could do with aliens on their side too.

And even that had gone poorly. A fight with an alien prisoner called Vartox had lead to her being rescued by her sister and the DEO; he’d even managed to cut her with an alien weapon.

Back at the DEO’s underground base, Kara recovered.

“Are you ok?” Alex, her sister, said.

“Y-yeah,” Kara said, breathless. “Just not really used to it.”

“What happened?” Alex said.

“He was pretty strong,” Kara said. She hesitated. “It felt like I was stronger, to start with, but he got a second wind. I don’t know, I just started to feel… sluggish. Might be out of practise.”

A member of the DEO’s medical staff came in, holding a sheaf of documents. Alex took it, her own medical training making it easy to read through.

Her expression shifted slightly as she read down the pages, occasionally flicking back.

“Alex?” Kara said.

“There might be more to it than that,” Alex said slowly.

“What do you mean?” Kara said.

“You know how your powers work, right?” Alex said. “The Earth’s yellow Sun basically charges you. Using Superman as an example, there have been times he’s been noted to run out of power after expelling too much at once; I think it’s called a solar flare. After that it’s just a matter of recharging, for him at least, then something to push him to… unlock them again.”

“I didn’t lose my powers,” Kara said.

“No,” Alex said. She hesitated. “But your physiology is a little… different. Clark grew up on Earth, spent his formative years here; you grew up on Krypton. His body is more adept at storing solar energy because of that, you never needed that capacity growing up so it never developed. Not to the same extent.”

“So, what, he’s stronger?” Kara said. She pouted.

“It’s complicated,” Alex said. She sighed. “Kara, don’t keep interrupting, this is serious. And really kinda complicated, I understand most of this, but… By kryptonian standards, Clark’s muscles are basically atrophied, he never really needed to exert himself consistently. Growing up on Krypton, yours are more developed naturally. That might act as a balance, but that’s not what’s important.”

Alex scanned the sheet again, making sure she was correct.

“If this is right, and if what you said about the battle was right,” Alex said, “Your body uses up its stored solar energy faster than it takes it in.”

Kara stared. Even just by Alex’s tone, she could tell that wasn’t good.

“What does that mean?” Kara said. “I can’t… be Supergirl?”

“I’m not sure,” Alex said. She hesitated again.

“What aren’t you saying?” Kara said. “I’ve had plenty of practise at reading your expression, I know when you’re hiding something.”

“Um, there might be a workaround,” Alex said. “If you do the majority of your work in broad daylight, outside, and, uh, expose yourself to a bit more sunlight then you should be able to replenish your solar energy quickly enough. You wouldn’t feel sluggish, like you did against Vartox; you’d be at full power all the time, not running low as soon as it gets serious.”

“I did fight him in broad daylight!” Kara said. “It didn’t help.”

“I know,” Alex said. Her cheeks coloured slightly. “The problem is, uh, your costume.”

“What about my costume?” Kara said, looking down at it.

The red S, the crest of her House. The cape, the blue, the red skirt, the stockings, the boots…

“It’s blocking most of your body from taking in sunlight,” Alex said. “It’s like going into battle with both hands and a leg tied behind your back, it’s limiting you. A lot.”

“Oh,” Kara said. She looked down, flushing a little. “I guess I could go without the stockings.”

“You, um, might need to do without more than that,” Alex said.

“What?” Kara said. “How much?”

Alex faltered.

“Alex!” Kara said, suddenly nervous. “If I want to be Supergirl, how much can I wear?!”

Alex glanced at the documents again, double-checking.

“According to this,” Alex said. “With your proportions, average strength of the sunlight in National City, and assuming you’ll want to be at full power for just three hours at a time before it starts to wane and, uh..”

“Alex, just tell me!”

“Two centimeters square,” Alex said. “Total. That’s how much surface area of your body you can afford to cover if you don’t want to keep losing your powers.”