Mmmmmm, they work so well together. They need each other. The sex is needy, clawing at each other, very physical, yummmmm ;D
Tonks is so different from Narcissa and Lucius from Remus that they both need the other's company.
Of course we know very little about the way Lucius/Narcissa work as a couple but I'm certain that Tonks is very different from her aunt. "You weren’t as sparkling as you’d been." Sparkling... I like Narcissa (especially in the scene where they're in the DE meeting and Voldemort kills the Muggle Studies Professor - she seems the grounding force for Lucius and Draco there) but sparkling.. she's not. Too proper.
And Lucius vs Remus - again huge difference. "With Remus, she’d grown used to simple gifts, flowers or a cup of tea waiting for her when she got home from the Ministry." This seems typically Remus, thoughtful signs of affection. I can't see Lucius doing that. His signs of affection - with Tonks - is that he wants to talk. And I'm sure she's right that he gives Narcissa plenty of jewels. Both because Narcissa will expect this but also because her wearing them shows off his wealth to the world.
*facepalm* Can you tell this fic has really got me thinking? *giggles*
I'm trying to imagine homelife at Malfoy Manor. Lucius and Narcissa alone - with Draco at school or off somewhere. What do they do? Do they even spend time together, like sitting in the same room in the evening talking or each reading a book or something? I somehow find that difficult to imagine. Of course I can always blame that assumption on my own Malfoy muses and their ideas about Lucius. :P