ichigo and uryu are brothers OR cousins. meaning there was a love triangle with their dads and this one quincy woman OR ichigo's dad was doin ryūken ishida's sister. i mean why else would mortal enemies(reaper and quincy-isshin kurosaki and ryūken ishida) be so civil to one another? why else would they both be in the human world alienating themselves from their respective clans?

because of a blood tie. ryūken probably hates and blames isshin for his sister's death. or he could hate him because he stole his woman and left little uryu mother less.
but when i put it like that it sounds bad.

ichigo's mother was probably ryūken ishida's sister.