Tenenbaum's mouth thins with distaste.

"And so you tell him you are his friend?" It's not a great leap -- Jack seems cool with Sinclair and she doubts that would be the case if Sinclair was being openly manipulative. "Until you do not need him? Tread carefully. The last man to do this, it did not go so well for him."

Of course, that's less of a warning and more of a 'you're going to get yours and good riddance'.