Even my trolls (with the expectation of my warrior) have a rp background though I don't rp on my trolls. Being a bloodthirsty monster is good enough rp for trolls.
As for the character development of Idra, much of it was inspired by my family background and my experience in the Blue Ridge Mountains when I went to school there.
I come from 3 generations of Baptist ministers. My great-great-grandfather, great-grandfather and my grandfather were Baptist ministers. There's an indication that my grandfather may have actually been a fifth generation minister. Grandaddy Smith was very much a mainstream minister though.
When I went to school in the mountains, I met quite a few ... ah.. characters who belonged to what my old neighborhood would consider fringe churches. I grew up in a well-heeled neighborhood.
There were Pentecostals, snake handlers (great way to get snake bit in the name of Jesus), and the most common kind in my neck of woods: fundamentalists.
You can see where I get ideas for Idra's rp. GOP helps too.
I have always considered Idra my most difficult alt to rp. For one, her rp calls for her to be cruel to those she consider below her. I, the player of Idra, find it very difficult to be cruel to others. In many ways, she's very much the polar opposite of me personality wise.
However, I did find a way around this. My humor can be dark. I thought it'd be well suited for Idra. I remember telling some Accepted that I charged 300 crowns for an item and for Tower members - an arm and leg literally - for the same item.
However, I remember nearly skipping a beat when some hol rp'er talked about lighting witches hair on fire. I wad shocked; I hoped no one noticed. I, the player, rarely ever agree with Idra.
Anyone who has ever hung around my alts will tell you that I'm very talkative; *oL are supposed to be the aloof type, and I'm anything but!
However, I can disparage or disdain members of the Tower to others around me or those I deem unworthy of the light.
There are other parts of me that I intend to incorporate into my other alts.
For example, I remember wanting to be Brown Ajah on my first fc. I used my fine arts and graphic design background for this rp; i drew pictures much like the kind you see in biology books, illustrated field books, etc as assignments to one of the Brown AS.
Just thought i'd throw out ideas for rp for your alts. I'm not the greatest rp'r ever but i think I can hold my own among the best.