For want of a title...
That either makes me think Ranma or King of Fighters.
With Ranma, eh maybe some supposed one time thing. Can't really think of any possible good ideas at the moment.
With King of Fighters...oh thinking about Negi with Orochi Tainted Blood instead of having Orochi sealed in his body. Gotten an idea of Negi being a bastard child of Goenitz who raped Nagi's wife. Not likely to happen if I recall about Goenitz but could have him thinking of expanding the ranks of those with Orochi blood in terms of berserkers/cannon fodder.
Why Goenitz and not any other Orochi follower? Well other than Vice and Mature, who are women BTW (and can't really pregant another woman unless they grew dicks or something), the rest of the Orochi followers are men and women around the ages of their twenties or so. Considering that Negi's about ten years old around the year 2002, Goenitz is about the only one of (at least proper) age to screw a woman. (I don't know the ages of Yamazaki or Yashiro but I suppose they would be willing to rape a woman if it's for Orochi's revival)
Secondly, Goenitz was/is called "The Heavenly King of Wind" which fits in with Negi who's a Wind/Thunder mage as I recall. (Which gives off the idea that Negi's possible mother can be Shermie (Heavenly Queen of Lightning), who married Nagi, or that Shermie and Goenitz screwed each other, her getting pregnant and both leaving the baby for some reason for Nagi to find and adopt)
With Orochi blood in Negi's veins, it could give a possible reason of why Negi's so strong even if he's just a Mage in training and why his preferred spells are of the Wind and Thunder/Lightning elements.
Considering in Negima where Negi knows how to fight in hand to hand combat and came second place in a (somewhat) major tournament where it had Chi/Ki blasts, magic, super powered foes and other things I don't feel like mentioning, I'd bet that KoF will give Negi an invitation to join despite how young he is. If Negi refuses to join up, someone in KoF could appear or somebody else to inform him with maybe information about his father for one. His possible teammates for the tournament? Either Setsuna, Kaede or Ku Fei. Maybe Chachamaru and Asuna as well, but Chachamaru is usually near Evangeline to serve her in any way possible (which could rule her out as Principal Konoe could likely die from making sure that Evangeline goes outside of the barrier that limits her) and Asuna more or less is still a beginner as I recall.
Blah, too much time on my hands to think this crap up. Time to eat.