Problem dealing with death as an atheist

[Zenith]

Which personality would you mean? The personality you had as a child? As an adult? You mean that a personality developed due to brain trauma is 'less real'? But what if a person becomes mucxh nicer after a brain trauma? It happens. That's just temporary and lost in some way? And what if a baby would get brain damage at birth? What is his 'true personality?'
What is 'personality' anyways. Some traits may seem inherent for a person, and they may be, but people develop a lot of traits due to the way they have been raised.

I define the "personality" (perhaps, wrongly) as "how you are like".
If the "brain damage" means that the brain is incapable to work as it should (perhaps making the boy a retard or something), then I won't consider that a part of "personality".