"He's got a wife and kids, you know," Wufei said, and Duo went very still. "A boy and a girl."
"Of course he fucking does," Duo spat, pushing up to stand and pace again. "Perfect fucking Oliver with his perfect fucking life . Beautiful wife and two point four children –"
"Your niece and nephew," Wufei interrupted, standing too. He wasn't as tall as Duo, but it had the intended effect, quelling the other man's anger now he wasn't towering above the whole room. The braided man drew in a little, the needle on his mood swinging slightly away from anger and back towards sulky. "Your sister-in-law. There's a whole family out there, your family, if you can stop behaving like a child for half an hour."
The last bit was unnecessary, and it put Duo's hackles up, but Wufei was feeling fairly testy himself for being in the middle of this, and extremely off kilter, so the scathing look he shot Duo in response was enough to forestall whatever expletive the other man had been about to fling at him and instead he just bristled in silence.
"It's already been made pretty clear that I wasn't wanted in that family unit," Duo muttered sourly. "I don't need to be told twice."
If you said the word "brother" to Duo Maxwell, he'd think of the other pilots. If you said, "no, your long-lost brother" to Duo Maxwell, he'd think of Solo and be very confused. If you said, "no, your twin brother you were separated from at birth, and he's now working with the Preventers as a lawyer" to Duo Maxwell, he would go and punch his doppelganger. Duo Maxwell isn't good at dealing with things, but unfortunately this particular thing isn't going to go away that easily.
My notes: The tag "Duo is a stressed-out jerk who needs a holiday" is exceptionally accurate here. He is angry, frustrated and pining, and that's before confronting a brother who didn't have to grow up in the war-torn slums of L2. CW for some Preventers-level violence. The banter between the pilots is pretty top-notch, too.