Ten gives Donna a small, 'thank you' blink and reassuring face. He can't help but be overly concerned about everyone coming in from different points on the timeline and information coming out - important information before it should.

Ten winces when Donna uses Time Lord out loud at least on the inside but Donna should see that and draws himself closer and states in a whisper, "I'm the only one here." Which is a lie. Ten knows 'Granddad' or one of his future selves is here. Ten gives a silent look of no needing to shout that Time Lord business.

Then continues to whisper,

"Just because you're human don't be going and be littling yourself. In fact - there's a lot of people here are. And they are the most interesting and amazing! In so many ways.. Just like you are."

Then a pause, "Me. You and Rose. I'm not letting anything happen to either of you."

He really doesn't want the Time Lord thing to get out. He's not ready. He doesn't have his abilities. He doesn't have a place where he can hide for awhile. He knows there are some very dangerous creatures/people here. Which Ten doesn't know what fully what they can do. Not in a place where reality is what you will it to be.

On top of not wanting requests from everyone to help fix their universes time flaws for their own selfish purposes most likely.

"Let's not talk about what I am outside. Too many ears. And there's no running away from this place."