And... well here is one Harry/Sekirei Xover idea:
Harry replaces Minato, having his Sekirei,
Harry is actually Takami's and Minaka's son also brother to Yukari (he replaces Minato in every way, Minato no longer exits, only Harry Potter),
Harry will still learn about magic (so he is not a Squib!), via letter,
Sorry, but no switching around any other Sekirei! Unless otherwise stated.
Harry is at least partially raised by Takami, and recognized by Yukari as her Onii-Chan (Big Brother).
Preferred, not necessary:
Homura does not change as much,
Harry also gets Karasuba (taming her a bit... not to much) and (maybe) Haihane (possible to re-wing),
Very much would love for Harry to be able to wing Akitsu (preferably for a long time),
Dursley's (if Harry stays with them) are physically abusive (a few scars and bruises or so),
Most events to be similar,
Harry is not mean and does not forcibly wing sekirei,
Confirmed as forcibly winged Sekirei can be re-winged as Harry's Sekirei,
Harry's personality is still at least vaguely recognizable as Harry's or Minato's.
Gap fillers (ideas for what you could use):
Harry was blood-adopted by Lily and James Potter, after a suggestion from the Headmaster (whether or not he is evil and stole Harry, or Harry was up for adoption, or etc. is your choice),
Harry stays with the Dursley's for enough time that he will remember them,
Harry has a few nightmares about the Dursley's,
Harry's personality, and the story's rating can be your Plaything.
*Due to some errors on Fanfiction, I had to remove all stylized text*