All kids are different, mine have remained relatively the same since birth.
Oldest boy:
As a baby-only preferred mom, dad or grandma to hold him. Had colic the first three months and to this day is a moody child. He has always hated being the center of attention ... HATES IT, even when Happy Birthday is sung to him. He's old enough now to learn to accept it, but in the past all he did was cry. He's definitely an introvert now. He's a shy and odd kid ... it's difficult for him to make new friends.
Youngest boy:
As a baby-he was perfect. He was that baby that makes people want to have babies. He loved being passed around and was generally happy all the time. Now he's a bit of a clown and loves showing off for others. Making friends is very easy for him. Always been an extrovert.
I really don't see either of them changing, but I never say never.