You were sent by the Tallest to keep an eye on your brother, Zim doesn’t do anything stupid.

Zim was thinking of a new plan to take over Earth. You had to watch him.

Gir was watching My Little Pony. Zim thinks it’s stupid. You let Gir watch it. It’s not hurting anyone. Zim just made sure Gir wouldn’t watch anything childish in front of the Tallest.