And then they're falling -- or she's falling -- because her mind isn't programmed to handle extenuating circumstances, and so when faced with overwhelming hatred that isn't provided in a way that's physically harmful, she doesn't really know what to do. Usually, this is when the small part of her mind that's still human takes over, kissing back or holding hands or whatever humans were expected to do.

Only Jade's human mind stopped aging at around sixteen, so currently her brain is doing backflips at being kissed by (a rather sharp, scary) Dave Strider. She hasn't kissed anyone in so long that she's not quite sure what to do.

So Jade's body goes into lockdown, sending her plummeting for the cityscape below.