Some thoughts on Nadder, bc i've been thinking about him today...
Quite old, over 1000 years
Was possibly once one of the greatest empresses whatever horrible continent this is has ever seen. It would make sense to me that the double body (two brains!) situation lent a certain potency to her psychic powers, perhaps in her youth she controlled one of the largest territories ever held by a single Lamia, a very formidable person
Non-Lamia people don't understand her situation and think of him as an odd.. uh strangely... touchy-feely.. brother-sister pair. Due to the gender dynamics with Lamia, "Asp" is often completely ignored, and Adder is seen as the main body, the true ruler, who people actually address or defer too.
Other Lamia can see how she thinks, and would understand that he's a single person, but are still confused and intrigued by him, mostly in the area of gender. The female component overrides the male, usually, in terms of how people conceptualize her. Is he half male-half female? or a female who was fused with her brother. Regardless, he's almost exclusively gendered female by the people who interact with him.
Her own feelings on this aren't very clear cut.
Her empire was toppled when Asp was kidnapped in a siege, something that functionally ripped his mind in half for as long as the two bodies were separated. Asp was eventually recovered, but the damage was pretty well done, and she's never really been the same.
Currently lives in a very old castle by the sea, and doesn't control any area greater than the surrounding village. His presence is mostly a historical curiosity, since his period of peak relevancy was at this point over 700 years ago, though I think his village is fond of him in the sort of oblique way you get with most haunted castles. They bring him food and gifts and like, and are quietly appreciated for it. Not particularly interested in drawing attention to herself.
His hair has always been white/silver, it isn't gone gray. These things age like dragons, which is to say unevenly. I do simply like the idea of her looking a little aged tho, it feels right. kind of worn
Nadder is an entirely nondiagetic nickname. Lamia communicate telepathically and don't use names for eachother at all, and non-Lamias just refer to him separately as Asp and Adder. The Nadder/"And Adder" pun would also be kind of dicey and flippant to say to her face lol