[She almost leaves the conversation at that, as the emotions she's feeling are so heavy that she almost can't breathe. The weight against her chest is mounting to the point she feels close to hyperventilating or crying. The initial reaction is to run from having to discuss things like this, even if she's the one that initiated the conversation in the first place.]

Hope is always good, but it's better to be realistic. Prepare for the worst so we can be surprised when something better happens.

[And in that moment, she realizes that's how she's spent so much of the last year of her life. The risks grew greater and greater on each adventure she and the Doctor went on. She became more and more reckless, valuing her life so little that she was willing to just throw it away in the name of keeping someone else alive. She had been so focused on preparing for the worst in every other outing that she hadn't even given herself time to look for a better path.

Maybe that was her purpose for being here. To fix that by teaching herself to look for the good again, to find ways to make something better happen. For both herself and the Doctor.

She doesn't leave as she had been planning. She doesn't sit back down, but stands beside him.]

You have to promise me that you'll be careful not to make yourself too useful.