If Gwynedd and Torenth were to face a common enemy, that would do a great deal to put the last nail into their traditional animosity.
It might, but I suspect not without a very prickly period first. The bad blood between Gwynedd and Torenth goes back over four centuries. The threat from outside, and the intermarriages noted in the Codex
(Liam to wed a relative of Kelson's and either Rory or Payne to wed a relative of Liam's-I don't have my own copy of the Codex
, and my recall is fuzzy at best) might help, but it might take some fighting first, with true rapprochement
only coming as members of both the Gwyneddian and Torenthi camps take each other's measure--seeing their old foes holding up well in combat, or otherwise demonstrating loyalty to the new joint cause. And really, that's largely how the Deryni regain their place in Gwynedd, isn't it? "By their fruits, you shall know them..."