It's our tradition, just the three of us—family night. (1.1-3)
Jason is a total family man. It's not just that he makes the extra effort to spend time with his wife and son, but that he also seems to enjoy that time more than anything else in his life, time spent doing scientific experimentation included.
I love my son. He means everything to me. And yet, I can't escape the feeling that I'm failing him. (1.49)
It's not easy to raise a teenager—trust us, we were teenagers, too. As we see here, Jason is struggling to navigate his changing relationship with his now hormone-ridden son.
"I had told you the day before that I was pregnant. [...] You came to my loft and said it was the hardest decision you'd ever made, but you were busy with your research." (5.481)
Our Jason gives up his dream to become a research scientist so he can raise a family with Daniela, but Jason2 makes the exact opposite choice. This has a huge impact on his life, leading him to invent a vehicle for multidimensional travel. Pretty cool. Still, it's clear that the guy regrets this decision. He wouldn't have kidnapped Jason otherwise.
Speaking of Charlie, Jason is also different with their son.
More lenient, less paternal.
As if he's forgotten how to be a father to a teenager. (9.17-19)
Jason2 is a much different father from our Jason. That's unsurprising: he's never been a dad before. Starting your career as a parent with a teenager is like starting a video game on the final boss with the difficulty setting ratcheted up to extra hard.
"Where's Charlie?" I ask.
She shakes her head, and as the tears stream, coughs a bloody sob into the bend of her elbow. (10.246-247)
In one universe, Jason confronts his worst fear: the death of his family. It's horrifying. As the book notes, Jason's fear is rooted in the fact that his mother died of illness during his youth, leaving an emotional scar that hasn't fully healed. He doesn't want to lose anyone else.
And inversely, there are worlds where I stayed and we had Charlie, which branched into less-than-perfect timelines. (11.209)
Over the course of his travels, Jason realizes that his life isn't a zero-sum equation between being the perfect family man and the perfect research scientist. Instead, it's a wide range of possibilities, many of which don't necessarily include a good home life for his wife and kids.
If I represent the pinnacle of family success for all the Jason Dessens, Jason2 represents the professional and creative apex. (11.214)
See what we mean? Jason could have easily stayed with Daniela but balked when he had to take care of his son. Or he could have fallen in love with a coworker and gotten divorced. There are many ways that his idyllic family could be much less idyllic. But the Jason we know is a good guy who seems to have made the right decisions.
I say, "For the first time, I think I understand how the Jason you knew might have done what he did to me." (11.345)
As Jason sees parallel versions of himself and Daniela, he starts to understand why Jason2 stole his life from him. He misses Daniela and Charlie—a whole lot—and he'd do anything to get them back, even if that requires doing things that seem straight-up immoral.
I am not a violent person.
But if I want my family back, there's simply no way around it.
I have to do a terrible thing. (13.73-77)
Even when Jason returns to his home universe, he's forced to consider killing other Jasons in order to get his family back. A little shady, true, but this further emphasizes his commitment and love for his family. We think. Another question: which Jason should get precedence, and why? Aren't they all technically equal?
The Jason beside him says, "This isn't about him. It's about what she wants. What our son needs. That's all that matters now. Let them pass. All of you." (15.64)
Although the army of Jasons want Daniela and Charlie for themselves, they realize that Daniela and Charlie deserve to make their own choice about which Jason they want to be with. If the Jason army didn't do that, these Jasons would be just as much of a monster as Jason2—and that dude is a legit maniac.