He doesn't like unnerving Steve. He can tell that something is wrong -- not sure what yet, but maybe he's done something wrong already. He'd been doing alright until the sight of Steve, apparently not feeling well, set off alarm bells in his brain. He hesitates upon answering. He's seen no signs of HYDRA, nothing suspicious other than being suddenly transported somewhere else and having a bit of magic, so there's nothing to run from. He shouldn't run from his mission. Friend. Top priority.

"Not from you." He really means 'not if you're here', he knows in his bones he should keep an eye on Steve, but all these jumbled memories are making it a little hard to concentrate. There is, however, one more important issue.

"You're sick." It's almost accusatory. What did you do this time, Stevie?