Okay, it's been awhile since I've done one of my crazy speculations/theories but...
What if Kindred is Gwen Stacy? More specifically, Gwen Stacy from Dead No More: The Clone Conspiracy?
Remember, Clone Conspiracy established that Gwen was actually conscious during "The Night Gwen Stacy Died" and thus learned that Spider-Man was Peter Parker. This also means that she blamed Peter for her father's death. Yes, Gwen forgave Peter during Clone Conspiracy, but let's also remember she underwent clone degeneration during that arc, too. What if she survived, but the partial degeneration also drove her insane?
Also, if you think Gwen being Kindred is nuts, it actually tracks quite well. The choice of calling him/herself Kindred? It alludes to Spider-Man and him/herself being Kindred Spirits? Hasn't it been said that Peter and Gwen, as lovers, were Kindred Spirits themselves? Look at Kindred's body type. The way Ryan Ottley draws him/her in the latest issue, he/she looks more feminine than masculine, even androgynous.
Look back, too, at those scenes between Kindred and Norman Osborn in ASM #30 and #31. The dialogue makes it sound like Kindred could be Harry, but if you read with the mindset that Kindred is Gwen, it totally fits. Especially when Norman talks about Kindred being his true "Legacy." After all, what is the Green Goblin's real legacy? He's the one indirectly responsible for Gwen death, one of the biggest blows Spider-Man ever had on par with the death of Uncle Ben. Speaking of which, what is the one sin Peter has refused to acknowledge to the point that he "barely even [remembers] it at all"? It's that he, not Norman, actually killed Gwen. She didn't die after the Green Goblin pushed her off the Brooklyn Bridge; she died when Peter tried to save her with his webbing, and the webbing accidentally snapped and broke her neck.
Also, if Gwen is Kindred, it totally fits with why Kindred believes Peter, as Spider-Man, endangers those he loves. It fits with why Kindred was actually protective of Mary Jane when you consider that MJ and Gwen were best friends. It fits with why Kindred was so angry that Peter re-revealed his secret identity to Black Cat; after all, Peter never revealed his identity to Gwen, the woman he loved. But he does to a former ex-girlfriend?
As for all of Kindred's demonic powers? Those can easily all be tech based, and all the allusions towards One More Day are deliberate red herrings (notice, too, it's never been outright stated in any issue that Kindred is connected to One More Day. That's an assumption we, as readers, are deliberately intended to make on the basis of Kindred's abilities and Mysterio talking about how he died and came back from Hell during PAD's Friendly Neighborhood Spider-Man, which was later retconned as, "Quentin Beck never died. It was just another illusion.") After all, Mysterio does the same thing by making it look like he has supernatural powers when he really doesn't, and it seems like more than coincidental that he's in servitude to Kindred. Plus, wouldn't it be ironic that the Master of Illusion is duped by his own gimmick?
Keep in mind, this is just a theory, so I very well could be wrong.