There's a reason why "da da" was Ryan's first word. It's because he's completely and totally fascinated with his daddy.
When Tony walks into the room, Ryan's face literally lights up.
When I'm feeding Ryan, he waves to daddy at least 5 or 6 times.
When Tony sings to Ryan, he squeals with delight.
Tony says Ryan does the same to me, but I know better. There is something special about their bond. I think it's because Tony's a single dad about once a month and they have their male bonding time without mommy around.
And knowing daddy will sneak a treat for him doesn't hurt either...