NPC Locations and Enemies

So, gameplay reasons aside, the location of NPCs like Rhea, Andre, Ingward and Shiva doesn't strike anyone as odd? I mean, some of them (Reah and Shiva, for example) are literaly meters away from an aggresive mob.

Or is there any lore explanation?

Andre and Shiva can handle themselves. And Reah is very spiritual.

It's just the game mechanics afaik. Generic enemies won't attack NPCs unless they accidentally hit them while aiming for you. I have tried to lure all kinds of enemies to attack NPCs, but they won't even retaliate, only summoned phantoms will.
Demon's souls was the same, the only exception was Ostrava.

Well, Shiva isn't really by angry mobs is he?
And I'm pretty sure Adrei is strong...

Actually you forgot Quelana too, and on several approches with aggroed wasps they ended up turning around when I touched dirt and disengaged me. I do believe I have had a chaos spider thing do that as well once but usually those die anyhow.

Well, Shiva's got a Crag Spider back there, just a few meters from his bodyguard. You can use it to kill the Ninja!

And since Queelag's Domain is so close to Blighttown, and Queelana is a Daughter of Chaos, I guessed she wouldn't be attacked by all that stuff down there. Lorewise at least.