I get [influence:success] when I ask him about why he looks familiar to me, and as we go down that line, we eventually reach the point where I offer to train him as a Jedi. But, alas, the problem is as follows...
He says that he left the Jedi because I did, and then I get three conversation options:
1) I'm sorry that my leaving for the war had such consequences...
2) It was not my intention to leave...
3) It's good that you turned from the Jedi...
Now, I'm a goody-good lightsider, so I choose the first option. And then Disciple's audio says Perhaps... about the path I walked., while the subtitle text is There is nothing to be done.... My reply options are:
1) (train him as a Jedi)
2) What are you doing for the Republic?
3) Are you a spy for the Senate?
4) (ask some other questions)
5) I'll be going now.