Two things I've been wondering about.
1)
In my first playthrough, I clearly remember, every now and then, seeing Gehrman in the area with the stump messengers (the ones you can give little hats to). When talking to him he'd just mumble on some stuff, seemingly sleep-talking to Laurence, I don't remember clearly what he said because it was a while ago.
To this day, in NG+ or NG++ or in my newer playthroughs, I've revisited this same area at different points of the game and I have never seen him again.
So what triggers these appearances? I kind of want to re-hear what he was saying now that I know more about the game's lore and story, but I can't get him to re-appear there.
2)
The first time I co-oped, I was helping a friend with Rom during my first playthrough. We used a password and he rang his bell in Byrgenwerth. When I arrived in his world, it spawned a bell maiden. We got invaded, killed the invader, then later killed the bell maiden. So I assumed that summoning a cooperator opened yourself to invasions. This was before the first main patch (the one that improved loading times).
But, I've been doing a coop playthrough now with two different people (as of the most recent patch), and we haven't had a bell maiden spawn at all so far. We cooped Cleric Beast, Father Gascoigne, Blood-Starved Beast, Darkbeast Paarl (pre-Rom, from the Hypogean Gaol kidnapping), and the first Pthumeru chalice dungeon.
So how does this work exactly? I thought that beckoning a cooperator would automatically spawn a bell maiden, but it appears it doesn't anymore? Is it random, only in specific levels, or what?