With everything under the Doctor's belt, he had to remain a shining force of optimism in the universe. No matter how difficult things became, risking the belief others had in him by a slip in a smile proved out of the question. It didn't matter how much he suffered so long as the universe itself remained intact.
It remained especially true when it came to people he--well, people like Rose Tyler.
"Love a good pirate ship," he voiced with some semblance of cheer. "Ought to go check it out, see if we can't get forced to walk a plank. Never gotten to walk a plank before."
At her last question, his expression substantially softened. He looked down at the floor, hands twisting together between his legs, and he gave a solemn nod. Perhaps he didn't need to continue to hide so much from her, but hadn't he already asked too much of her just by spending what little time they did together? Difficult to make up his mind on the matter, the Doctor settled on uncomfortably clearing his throat of any potential sign of anxiety and nodded again.
"Yes, ah. Of course. Are you alright?" Shifting his concern to her helped, and it was punctuated by a matching look sent her way. Wordlessly, he slid over to offer Rose a place to sit next to him. He'd deny her nothing.