In defence of Zevran he only has nothing to say if you don't get his approval rating up, and that is the same with many of the characters, Sten is one who really springs to mind: "Care to talk?" "No". First time I never got Sten up high enough for him to divulge about his sword. There are some things Zevran will only talk about if you are romanced but I still got the confession about his reason for taking the mission as a friend. My girl elf mage, who was besotted with Alistair and so never so much as looked at Zevran as anything other than a friend, was thrilled that after defeating the archdemon Zevran asked to stick around as a sort of mascot. She was only too glad to agree since she really got on well with him and I thought "lucky girl, you get Alistair and Zevran".
I was replaying the Temple of Mythal tonight and I noticed how the moment the door to the inner sanctum actually opened Solas said something along the lines of "So Mythal still endures." So it almost seemed that up until then he thought she was dead but seeing the magic of the place work made him reconsider. I wondered if originally he was only trying to get the orb back from Corypheus but that was the point where he makes up his mind to pursue old plans. Then there is the exchange with Abelas. After all it was only after the Well of Sorrows that he was apparently going to tell Lavellan everything but changed his mind. Did he not realise before then that there were so many survivors from the ancient days? It is also after then that you can have that talk where he says about waking up and finding everything worse than before. When he asks what you would do, I have to admit I walked right into it. "Keep on trying". I do sometimes wonder if I may have inadvertently encouraged him to continue on with his personal quest.
The reason I always feel so depressed by events is that after the Fade episode, where I saw his gravestone and his greatest fear was "To die alone", I had made up my mind that I would stick by him no matter what happened. He would never have to die alone if I had anything to do with it. My greatest fear was that in order to close the rift permanently, someone might have to do it from the other side and get shut in and he would volunteer. I thought he suspected this and that is why he said it would be kinder not to romance me. So when the relationship went to hell, I tried to console myself with "Well, at least he's not dead." Then came the epilogue and even that slim bit of comfort seemed in vain; we don't know for certain what happened but I don't think those glowing eyes bode well for the future.