Hi NekoNinja! Welcome to the site.
My reading was that they split. Teppic went off and did his own thing and left Ptraci (his sister) to rule the kingdom.
Unless I've missed something, it seems to me that he went back to the kingdom (she called for him back.)
'What will you do?' shouted Ptraci, leaning over the rail.
'And none of that,' she snapped.
'Don't you like being king?'
She hesitated. 'Yes,' she said. 'I do-'
'Of course you do,' said Teppic. 'It's in the blood. In the old days people would fight like tigers. Brothers against sisters, cousins against uncles. Dreadful.'
'But you don't have to go! I need you!'
'You've got advisers,' said Teppic mildly.
'I didn't mean that,' she snapped. 'Anyway, there's only Koomi, and he's no good.'
'You're lucky. I had Dios, and he was good. Koomi will be much better, you can learn a lot by not listening to what he has to say. You can go a long way with incompetent advisers. Besides, Chidder will help, I'm sure. He's full of ideas.'
She coloured. 'He advanced a few when we were on the ship.'
'There you are, then. I knew the two of you would get along like a house on fire.' Screams, flames, people running for safety .
'And you're going back to be an Assassin, are you?' she sneered.
'I don't think so. I've inhumed a pyramid, a pantheon and the entire old kingdom. It may be worth trying something else. By the way, you haven't been finding little green shoots springing up wherever you walk, have you?'
'No. What a stupid idea.'
Teppic relaxed. It really was all over, then. 'Don't let the grass grow under your feet, that's the important thing,' he said. 'And you haven't seen any seagulls around?'
'There's lots of them today, or didn't you notice?'
'Yes. That's good, I think.'
You Bastard watched them talk a little more, that peculiar trailing-off, desultory kind of conversation that two people of opposite sexes engage in when they have something else on their minds. It was much easier with camels, when the female merely had to check the male's methodology.
Then they kissed in a fairly chaste fashion, insofar as camels are any judge. A decision was reached.
You Bastard lost interest at this point, and decided to eat his lunch again.
It ends here and doesn't say if he leaves again. After that it just talks about Dios.