Precedent

Their first meeting – long overdue, technically – was with him suspended in an energy field, a prisoner to his non-biological grandfather.

Not that he would have recognized his biological grandfather, but that was beside the point.

And he doubted his blood grandfather was a Sith.

When confronted with aforesaid captor, his first word to him was "Traitor." Much more was said after that – a bid for power, that startling revelation, the insane notion that he would join him.

But years after his escape, Obi-wan had to laugh at the bitter irony of the other's first two, though mocking, words:

"Oh, no."

(The spelling of "Obi-wan" in this fic is completely intentional. In A New Hope in the original credits this was the correct spelling; the other spelling of "Obi-Wan" didn't appear until the books started coming out.)