Why would he pointlessly die by teleporting up to Dallis on the Vengeance? It's bugging my happiness, especially when the game will script other NPC's back to life, or script them dead when they live (Kerban!). Gareth makes an exteremely dumb tactical decision via the combat AI and dies to the detriment of your story game gameplay.
Now I have to go back to the Vengeance fight and hope he doesn't willfully kill himself again.

Thats weird, when i was on that part he jumped up that wooden flooring the ship has, not into dallis lol, and i tried that fight like 5 or 6 times