You Do Need power plug adapter while traveling from Nepal to Brunei.

Here is Why You Need An Adapter

The outlet and plug type used in Brunei is G and in Nepal are C, D and M. This is how they look like.

Nepal

In Nepal, outlets of type C, D and M are in use.

Type C

Type D

Type M

Brunei

In Brunei, outlets of type G are in use.

Type G