She doesn't seem deceitful, and while people can often be more than they seem Bruce also likes to think he has a good read on people. He's a detective by nature, looking for chinks in people's armors.
Bruce isn't used to being completely alone, he's always at least had Alfred. It's been a long time since he's worked with someone other than his butler but he's also begun to come around to the idea that that might not be such a good thing. He had been planning on working with Diana to find the other metas back home.
And it seems now he'll be working with Kara here -- whatever that ends up meaning.
Bruce laughs a little. "I can handle the science part just fine." He did synthesize kryptonite weapons on his own, after all. "Honestly? I mostly need someone to remind me to eat and sleep."
That may sound like a joke but Bruce's version of being a workaholic makes Cat Graham look reasonable.