Ian saying "Uuuuummmmm." Before answering any question.
Alex referring to people as 'Humans'.
Alex calling a flyer left by a yard maintenance company an 'email'.
Every single word that Ian mutters and repeatedly says, just because he knows he can.
Ian commanding Chip Chip with 'Sip Sip, Wait' or 'Sip Sip, Siiiit'.
Watching the two learn to play together, nicely.
Alex's fascination with building forts and then reading to herself for long periods of time inside.
Our dance parties.
Alex's love for hip hop beats.
Alex's curiosity and confusion about God, and her millions of questions about why he created this or that.
In a strange way, Ian's temper tantrums where he loses it for a moment throwing anything he can see or find and then immediately carrying on as if nothing happened.
Ian's complete love and adoration for Pop Pop.