@KittyTantrum Around 9 months they reach lots of great developmental milestones and one of them may flip your baby's preference for other people and make him prefer the most familiar people. Around his 2nd bday I'd go around your place and make sure there's nothing he may want to climb up to get, i.e., if he knows the cookies are on top of the kitchen counter, between 2 and 3 years old are when he'll stack up a bucket and a few toys and try and climb his way to the cookies.
Congrats!