OK. Here is something that seems very plausible to me.
Homuras wish was, to be popular and to excel at everything and this will explain alot.
When Mami and her meet in episode 3 about 1/3 through, there is a particual line.
"That sounds like something a person, who has been bullied her whole life would think.
So what i am thinking is, that Homura already was a student at Madokas school. Thats why she knows her and thats why she knows the school. Now through her wish to become popular and excel everywhere, it meant for the old Homura to disapear and a new different Homura transfers into school. Everyones memory of a weak little ugly girl, that was bullied all the time disapears.
Maybe madoka was her only friend or someone who at least tried to be nice to her or protect her. Maybe not and she just wants her not to become a magical girl, because if she does become a rival to her, her wish might be in danger, since it is fueled by defeating witches, like many have the theory here. Them being friends, supports that Homura actually seems to care about her happinies and lead her away from being a magical girl with words instead of attacking her.
There is also her making an angry face, when Madoka mentions her name is weird. Maybe because the other children used to tease her with it, call here really bad nicknames?
Thats basically how far my speculations go right now. Also some of the other thoughts in this thread are really insteresting. Hope to see more
