The blackmail route is something of a casualty of the dev's learning process. What it ultimately becomes (by the end of the prologue/start of Chapter 1, is "Love and Corruption".
They also aren't like traditional paths of the same name. The Dev breaks down how they work at the outset of Chapter 1 (7.0), so I'll use their words:
"Blackmail" is replaced by "Corruption".
An important thing to understand is that the MC is basically ALWAYS protective of his girls. Always. And from all indications, it doesn't seem that it ever will be malicious, or in a dark sense. They will always know MC has their back. But in the 'corruption' route, the relationship might be more based on physical relationships instead of emotional ones. (but even that's too simplistic)
Sophia seems like a perfect case. She appears to be the embodiment of a Corruption route - she's a complete horndog, intensely physical...but she also completely loves the MC, a little bit against her own wishes. In her origin story, MC took a bullet for her even though he didn't know her beyond her name - she was part of his 'pack', for however briefly, and you protect your pack.
And part of my delight in this game comes from the characters' not being at all obvious. At the outset, I checked off boxes like, "Ava - Love, Lila - Love, Jasmin - Corruption, Ashley - Love, Asuna - Corruption, Julie ??"
But I've almost completely flipped the mindset for them. I was dismissive of Jasmin at the outset, but she has surprising depth. Ashley seems like a Cuddle Bunny, but I'm getting a sense of she could be a bit freaky (and not because of the blue hair). I assumed Asuna was pure transactional, but I find I want to peel back the emotional layers. And Julie...man, I may just have to see what "Corrupt Julie" looks like out of pure fascination. I wouldn't be shocked if Julie turns out to be the biggest freak of all. But, um, that might just be wishful thinking....