He was not his father. He would never be like that man. (1.223)
Ah, that answers our previous question. But we're still not sure what Nick's problem is with his father. All we know is that Nick is glad he is not in the picture.
I'm the man of the family. It was his job to protect her. It was all he knew. (1.178)
Here the fact that Nick's mom is a single mother is alluded to, and it helps explain why the two are so protective of one another. But why is Nick's dad out of the picture? Does Nick think he is better off without his dad in the picture anymore?
He could handle insults directed at him. It was the ones against his mom that elevated him to fighting mad. (1.121)
Nick is very protective of his mother. She is also very protective of him, so it's a relationship that works out well.
Adarian Malachai was his father and he was a monster. (4.63)
With Nick's attitude toward his dad being totally negative, this sentence makes sense on that level. But we'll later learn that Nick's dad actually is some sort of monster. Any reference to a monster in this book is literal as well as metaphorical.
"My parents died a long time ago. And you know the sad thing? I still miss them every day. […] I swear to you, you'll miss them when they're gone." (6.112)
This sentence feels like foreshadowing. We doubt Nick would care if his dad died, but he would be devastated if anything happened to his mother. She's fine in this book, but we wonder what her fate looks like in the rest of the series.
The true monsters in this world, the people like his dad, were real and human through and through. Which was what made them so dangerous. (6.8)
This is a good line, but keeping in mind what we said earlier about the literal monsters in this world, this isn't exactly true. When we later get to know Nick's father a little more, we learn that he isn't entirely human. Does that make him less dangerous? Or does it make him more dangerous?
Nick didn't even want to think about his gene pool for fear of the infection it might contain. (9.236)
As much as we don't want to be like our parents, it can be inevitable. After all, you have their DNA in you, so you are probably much more similar to your father and mother than you'd like to admit. So is it nature or nurture? What does Nick think about it?
Soon there would be no way back from it. It would consume him and he would become his father. (13.173)
Many people say things like this as a joke, but for Nick, becoming his father is serious business. As we learn from Ambrose/future Nick, if Nick turns evil, he will become a Malachai like his father, and the safety of the world will be in danger. That's some serious business.
"You are killing your mother and brother." (15.12)
The bad guys capitalize on Madaug's guilt about hurting his family to lure him to them. Like Nick and his mother, Madaug is fond of his family. It's a trick of dictators and monsters everywhere: if you can't convince someone to do what you want, threaten the safety of those that person loves. It's nasty business, through and through.
Nicholas "Nick" Ambrosius Gautier
"We take care of my mom first—she's my number one priority. I have to make sure she's safe." (15.100)
In case you haven't caught by this point, Nick's mom is his number one priority. He risks his own safety to make sure she's safe, and it pays off.