I'm not sure what the plans (if any) are for expanding the directions the game can move in, but as it stands it seems like the Encrypted Scroll is the key. You give it to Petrus to get the GC, you give it to the dude in the dungeon to get TX. If we continue that pattern it seems to me that it will get awkward pretty quickly to write in.
What I propose, is that the scroll itself always
goes to Petrus. However, instead of immediately sending you into the GC, he then gives you permission to do errands for his courtiers while he confers with Haedlac. Chatting with him again gives the GC, while chatting with other people may give other quests. This opens up story possibilities without forcing the player to commit mail theft every time.
I like it, a lot. I only recently started playing a bit of Tomb of Xinroch and I gotta say, it doesn't make any sense at all that the necromancer in prison asks for the encrypted scroll. Specially since the story he tells you has absolutely nothing to do with it. It's just a cheap excuse to make you unable to enter the gloomy cave when going for the tomb. Also, it's weird that there's a whole lot of guards around the tomb, still you can enter it unchallenged? Furthermore, the "high lady" of the dark knights being female is really weird. It comes up to me as forced, trying to be politically correct and give women more important roles, which doesn't fit with the spirit of the game. Same with the lady in Attnam with a thunder hammer.
Also, there's no hint whatsoever that you can give the scroll to someone else. The game points directly at giving the scroll to Petrus, it's the first quest and it's pretty straightforward. Honestly, I'd like an expansion through the blue portal in Oree's room.
Ah, then consider this further endorsement.