Great - lets take a young player from Real, so that when he becomes a star, he can run to the press and tell them his heart has always been in Madrid and he yearns for a return.
That's what I suspect will happen. But that's the risk you have to take when signing any Spanish/Latin star - they will always want to go to Real Or Barca when those show any interest. See Xabi, Arbeloa, Mascherano and now Suarez. Even Man Utd. at their prime could not keep Ronaldo.