I dont trade the retinue traits between characters. I like to role play in that sense I guess, I figure whoever gets them should keep them, but then something occured to me - wouldn't it be great to spam several preists over to some highly orthodox area of the map and let them gain retinue, then move the retinue (full of piety) over to generals or other priests.

You could be pope or have a full piety general within 10 or 15 turns!