@IsoujiX
That's cause he really love his family and he include his twin in that family circle. Since he IS the eldest brother, in these type of chinese situation, the elder brother usually kept and give all the good stuff to the younger sibling. In this case, the little brother who's he's been...
Immortals dont have family thus when they encounter mortals that hold onto that ideal they lose. Its the same thing with westerner theme. Elves and Dragons.
@tutara
They can't cause they are girls in the prime of their life and that is an attractive strong male. Alpha instincts yo. HOWEVER he is old in the soul so he only see them as kids so in a way they dont see him as friends but he see them as grandkids. Good enough?