meh, i thing they simply don`t like necrons `cause a long long time ago one of the C`Tan (who`s reall name is Paul, but everybody calls him the Nightbringer since he caused a balck-out at a party while trying to plug it his home made 10.000 W sound system) stole the original 'overmind'`s (John) girl and they never talked again.
The grudge carried on for years and now they won`t even let their kids play with eachother because of this old fight
