what does it look like , narcissa telling lucius that draco isn't his son ? what are her emotions at ? how does the fact he got sent to prison and thus put draco at risk play into the situation ?
previously: some insight into the malfoy marriage.
Lucius takes more than sixteen years to realize out that Draco isn’t his. He probably should've figured it out sooner, but some people only see what they want to see and Lucius didn’t want to believe himself a c.uck.old. So he let himself be convinced that Draco took after Narcissa’s side of the family, though he held those genetics against Draco too.
Narcissa tells her son because she would rather Draco hear it from him than someone else. She tells Rabastan because it’s been so long and if Bella hasn’t let it slip yet, she wants him to hear it from her. She tells Rodolphus---or did he already know?---because he’s family and she needs him on their side.
She fails to tell Lucius because it isn’t a priority to her---Draco and Rabastan are her priority. Besides, she doesn’t trust him not to cock it all up for the rest of them. Narcissa figures she’ll let him know after everything is all sorted out, a parting shot on her way out the door.
Lucius has enough of his own shit to worry about in ‘95-’96 anyhow. Has to prove his loyalty to Voldemort, complete his mission to retrieve the prophecy, etc. He can’t even vent his stress by arguing with Narcissa. The Lestranges are back, are irrevocably on Narcissa’s side, and Lucius is uncomfortably outnumbered and outgunned. He finishes out the year in prison, none the wiser.
But after his release, it doesn’t take him long to figure out. Between Bella’s taunts and Draco’s uncanny resemblance to Rabastan, he’d have to be dead not to see the truth. The suspicions eat at him in the midst of the rest of what’s going on---the Dark Lord’s disapproval, his loss of power and respect in his own home---until he manages to get Narcissa alone and confront her about it.
Which isn’t easy. Though she isn’t a DE herself, Narcissa is rarely alone those days unless she’s in her room. So that’s where he corners her. He accuses her of i/nfidelity, of forcing him to raise another man’s child. She admits to it immediately; the cat’s out of the bag and she has nothing to lose.
The following argument is as vicious as it is quiet. They used to hide their arguments first from Abraxas himself and later on Draco. Secrecy is even more important now that their house has been taken over. Lucius calls her every nasty thing he can think of---frigid, bitch, adulteress---and a bunch of slurs I won’t repeat. Narcissa picks at every crack and fissure in his ego, takes him apart the way only she can, because no one knows him the way that she does.
I want to say that things got a little violent---or it had the potential to become that way. Because things got nasty to the point where it had to spill over: a rough grab, a push, a threat. There’s no way it wasn’t headed that way, and the only way for that to stop would be for there to be an interruption of some sort.
Someone walked in when Lucius had Narcissa’s arm in a bruising grip, a half-step into her space---maybe his other hand raised---while she spit out that he was trash and that he’d die unloved, unmourned, and with nothing to show for his shitty life.
And, so, that’s how Lucius found out.
