Something I've always found hilarious that was criminally glossed over is Marcus. So he's St. Marcus right? Well St. Marcus aka St. Mark aka John Mark aka THE GUY WHO FUCKING WROTE THE GOSPEL OF MARK??? Like yeah they talk about him being St. Marcus but they really ignore the fact that this means that he wrote a really important book of the BIBLE. There has to be so much there that smeyer doesn't cover. Do I only care about this because of my heavily indoctrinated religious upbringing? Yes.
Part of me believes that Carlisle learned about this and that's the whole reason he hung out with the Volturi for a hot minute.
Imagine Carlisle just sitting at the foot of Marcuses throne everyday like "PLEASE TELL ME MORE ABOUT WRITING THE BIBLE AND HANGING OUT WITH PAUL" and Marcus just sighs and looks off into the distance and says "not today I'm too sad" and Carlisles getting really frustrated like "that's what you've said every day for the past seven years!"
The real reason Carlisle left the volturi is because he wanted to learn about his lord and savior Jesus Christ straight from the source and got rejected. Also because he asked about the biblical story that mentions Mark running away naked and that pissed Marcus off.