On Kingpin and the future Mrs. Kingpin: Fisk's childhood trauma has less to do with encouraging the audience to sympathize than it does with explaining why Vanessa, to all appearances a decent woman, falls in love with him and remains devoted even after his criminal activity and merciless choices begin to show. His primary humanizing feature is her, not his past, and for that to make sense, we have to see how she's moved by pity and admiration into a relationship much stronger than it would be if based on something more obvious, like a desire to benefit from his wealth and protection. We get the evil first and its background later, but she sees his best side followed by sacrifices he made to get to it - rather like the way Matt is introduced to us. When Fisk reveals to Vanessa that he's behind the explosions, he does it by telling her that the men who kidnapped the little boy are dead - truth with a calculated omission, but when she replies, "Good," she's a step closer to his break-some-eggs mentality without feeling like she's compromised her own principles.
I don't think Vanessa started out as an angel and I don't think she's wholly bad at the end, but she's definitely a dangerous villain in the making, and a good example of the road to hell being paved with good intentions. She's also what makes Fisk unique. It's clear he loves her in a way that isn't even contaminated by his own immorality, which is why meeting them as a couple forces Matt to confront his own ethics in plotting Fisk's death. I fully expect Vanessa to be the one who breaks him out of prison and/or takes up leadership of the underground where he left off, and I can't wait.
On Kingpin and Daredevil: Fisk and Matt are presented as nemeses by playing up their parallels as well as their essential conflict. That's not that unusual but the symbolism at work makes it fun. Each has a trademark color, which are contrasting but not opposite, and an abstract painting in that color which is used to describe their personalities. (Fisk brings his painting home and wakes up to it every morning, Matt rejects his; what does that mean?) Matt uses his religion as guidance; Fisk says he can't pray. Matt claims to enjoy causing his enemies pain; Fisk is careful to stress that he doesn't take pleasure in breaking all those eggs.
The real center of their dichotomy is in their respective relationships to their shared hometown. Actually, the entire season is basically a territorial dispute between two men, and not in a symbolic way - the fictionalized Hell's Kitchen is more important as a setting than the MCU is. Fisk wants to improve on the city, supposedly because he loves it. Matt, as both a lawyer and a vigilante, wants to save it from Fisk. Their final confrontation is on the anticlimactic side in a lot of ways, one being that you keep expecting Daredevil to deliver a really cutting retort and instead he's mostly silent, but what he does say is more significant than it seems at first: "This is my city! My family!" Throughout the series, he's been calling Hell's Kitchen "my city". Fisk, without exception, refers to it as "this city". What's the difference? Hell's Kitchen gave Matt his father, St. Agnes, Foggy, Karen, Claire, Father Lantom, and a lot of innocent people who need him - a family. He's finally found the difference between himself and Fisk: he loves his home not for the sake of his own history there or the power he has over it, but for the people in it. The territory is his by right, because he's its protector, not its ruler.
On Matt and Foggy: If you read my complaint about the Family of Choice trope (used in reference to the Buffy comics but applicable to fiction in general), you'll know I'm not a fan of trying to upgrade one's friendships. However! Matt's found family makes a perfect exception to the rule, both in his connection to Hell's Kitchen that I just talked about, and his individual relationships, particularly the one he has with Foggy. For one thing, he's an actual orphan, with an early family life that was unsatisfactory because it was taken from him too soon, not because it was lacking in love. He tried to find a replacement for his father and failed because you can't choose to be someone's son, so he had to wait for a parental figure to come along of his own accord.
Foggy isn't an orphan, but he offers the kind of friendship that quickly becomes fraternal. You can also see that both of them parent each other in their own ways - Foggy by assisting with Matt's disability needs, Matt by taking a leadership role in their business. Probably the most prominent familial metaphor between them, though, is a marriage. It's inevitable that this instantly turned into a popular slash ship, but there's also something to it that doesn't involve sexuality at all. What's marriage? An exclusive commitment to another person, meant to provide a foundation for a shared future. Let's not try to sanctify the union of all business partners, but Foggy and Matt have something special in theirs: a belief that together they can make a difference in the world, and they trust each other enough to take a risk with it. I'm glad the characters made the comparison themselves, albeit humorously, because otherwise it would have been a real elephant in the room (I mean, the visuals alone, with them always going around on each other's arms, right?). But their relationship is a driving force in Matt's development, it's what makes Foggy a complex character of his own instead of the funny sidekick, and it's incredibly touching and worth more than a romance at this stage would have been for either of them.
I've got more but I think it's best if I space them out, plus I'm headed out of the office soon. It's a good thing I've got an episode of AoS to watch tonight, or I'd probably be like "well, time to start a third round of Daredevil..."