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

Here is Why You Need An Adapter

The outlet and plug type used in Ethiopia are C, F and G and in Brunei is G. This is how they look like.

Brunei

In Brunei, outlets of type G are in use.

Type G

Ethiopia

In Ethiopia, outlets of type C, F and G are in use.

Type C

Type F

Type G