[ Will puts his hand on her shoulder - he did warn her of his presence, and even so doesn't expect her to jump because the palliative effect of tribbles is just that strong - so he eases himself down to sit beside her a moment later, returning his hands to his own lap.
It's tempting to gather them up and pet them, but they're a blight, and Riker's concerns are in the same vein as Seven's. ]