If you're an Endorsement 6 or motorcycle Novice 1 licence holder, it's illegal for you to carry passengers while operating a motorcycle. Even with an Endorsement M Novice 2, or as an unrestricted motorcycle operator, you should avoid carrying passengers or large loads until you are an experienced rider. The extra weight changes the way the motorcycle handles – the way it balances, turns, speeds up and slows down.
When you do start to carry a passenger, carry someone who is light before carrying a heavy person.