She grinned and ran as if to meet him half way. As she did she threw whatever she had palmed while throwing herself into a tuck and roll to come up behind him while he was dealing with the small throwing dagger she had launched at his chest. The momentum from both her running and her tuck and roll helped negate the disadvantage throwing something upwards would usually have.

If he was distracted enough by the dagger to miss what she did when she popped up behind him, he's probably be very well aware of it when she dug her fingers into his flight feathers and made a fist, holding but not pulling, and ready to move with him to keep herself anchored at his back.