Jade never strays far. Artemis knows because she does the same thing, has become so used to measuring distances she's only conscious of it when she stumbles, when just-out-of-reach becomes unreachable or out-of-earshot becomes within. They don't talk, not to each other, not about each other. When Artemis joins her team, she's glad of it. Her dad may be unavoidable, but she and Jade, they've always known how to draw circles around each other, how to walk parallel lines.
When they fight Cheshire, it's been longer than Artemis can keep track of since she last saw Jade. Distance isn't the only balance Artemis keeps; there's weapons and heights, there's teamwork, there are many things. Juggling them is still far from second nature; when something feels wrong, Artemis doesn't immediately know what it is.
Right now, frankly, she's too busy to take notice of the prickly feeling on the back of her neck, too busy to chalk up her uncertainty to anything but stage fright, having people to impress.
Artemis shouldn't have to knock off Cheshire's mask to know who it is, and she can't believe seeing Jade catches her off her guard.
It's been so long, much longer than any person's big sister has any right to leave them alone.
All this time, this is the identity Jade must have been creating, a lone cat who hides in plain sight, smack in the middle of your line of vision.
It's a change, a shot, and Artemis's measured distances need adjustments. They're not running parallel anymore. They're converging: they've been drawing circles for years, keeping away, and looking at Jade, she knows she's letting her go, now and the next time this happens, and the next, because she knows just as certainly this isn't the last: all their stupid circles overlap.