You realize that what you're doing is creating a time paradox? Something we've both promised never to do?
If we were so intent on meeting with our younger, past selves, we'd go back and stop the Time War from ever happening. You see, that is how I know something is very wrong with you.
Secondly, I cannot, or shall I say, will not harm you. No, I could not kill myself, that would be counter productive. And a form of suicide, nasty thing.
If you don't help people anymore, then you have no right to the title Doctor, no. We made a vow to protect people, to help them. That is why we chose our name, and as for you, something has happened.
But what, what happened? You claim you've seen the truth, learned the truth. But what really is the truth? [Doctor's gonna put on his glasses and look at you closer thar]
You see, there's more to it than you're leading on, and that is why you are trying to push me down, to break me, but you cannot break yourself. Everything you alter now will alter you, techincally speaking. If anything happens to me, you don't exist and caput. We're dead.
But maybe that's your goal all along, maybe you want me to dead so that you never exist. Destroy the Doctor by impersonating the Doctor, and finding the past version of himself who is weak. Yes, I'll admit, you've caught me at a bad time, but that does not mean I'm not clever enough to figure you out.