I have lost Martin and Jauffre **answer may be a spoiler***

[Trinity's Quest]

I started off to the Cloud Temple, but was on a horse, so I left M and J behind. Well, they never arrived. Maybe they got killed, I don;t know. Can't find them anywhere, have retraced all my steps. Of course the gate won't open. I am very far along in my other quests. Do I have to start over or are they still standing around in the wilderness somewhere?
Sheesh. Kids these days.

[Arnfin]

You might try fast traveling back to Cloud Temple. When I fast traveled there they popped in right there with me. I doubt that anything happened to them, other then getting separated from you.

[Go Sens]

When you go over Martin and Jauffre with your targeting Reticule you will notice that instead of the usual "Talk" icon there is a crown icon. This icon means that they are essential characters. They cannot be killed because they are important to quests later on in the game.

[Trinity's Quest]

I have been back to the temple several times, on a horse, walking, walked all around. I even unlocked the gate with the console and went inside. No Martin. No Jauffre. And I went back to Kvatch. I think they ran off together.

[Go Sens]

Why dont you just plug in the code to skip that aprt of the quest

[Trinity's Quest]

Can you provide that code?