J.D Robb- AKA Nora Roberts.
Nora Roberts has a big ol' soft spot for Irish characters. Irish names, Irish characters, Irish settings, she loves them all. Roarke, from the In Death series, is Irish and is as sexy as hell. She has also penned numerous series and trilogies with an Irish focus, including Irish Dreams, The O'Hurleys and The Donovan Legacy.
Louise Bagshawe writes standalone romance books, full of throbbing cocks. And yet, this is not her tell.... anyone who has read any of her books knows that she has an obsession with describing clothes and makeup. You will know at all times exactly what her protagonist is wearing, and just how hot they look in that outfit.
Steph is another one who cant but seem to help squeezing in similar details into her books. Her heroes always seem to be honourable men who won't take advantage of the female protagonist, while her female protagonists are super-self-sacrificing to the point of becoming annoying.
P. C. Cast.
Amazingly enough, P. C. Cast has two tells! one big, and one small.
Small tell... In her goddess summoning series, it seems that the mothers' of the gods and demi-gods getting involved in their child's business is the main cause of mystical stuff happening to the mortal characters. Meddling mothers! Who'd have them!
Big tell... everything is very spiritual. There is a lot of ritual going on. Plus, women are amazing, empowered beings who kick ass, usually because they are inspired by the various goddesses and the whole spirituality of the thing. This crops up throughout both The House of Night Series and The Goddess Summoning Series.
These are just four that I have come up with off the top of my head. Do you have any favourite authors that have quirks that shine through in all of their books? Or can you think of an author that holds a completely unique voice in each of their books? Let me know what you think!!