The typical scenario involves Asuka being sent to Rei's place with homework instead of Shinji. She sees the state of Rei's living conditions, and is appalled. It isn't even a matter of empathy, really; she's horrified because Nerv is treating a pilot
like that. She isn't Rei's biggest fan, but even if she hated her (and she doesn't, really; Rei just pushes her buttons something fierce) treating a pilot like that will not stand
. It's a matter of principle for her, not friendship. That's just how Asuka works.
As for fics: Gob's played with it a bit, but the classic example is Once More With Feeling.
There are plenty of others that explore the subject (including lemons that have the two hooking up, though those are
OOC for both parties).
Arcadia's legacy wrote:
Was that really necessary?
Probably not. It's too late to edit it, but FWIW I apologize.