Rob Kardashian writes touching birthday message to his future stepson, King

Rob Kardashian shared this touching message to celebrate his future step son's birthday. His fiance, Blac Chyna's son King Cairo turned 4 years old Sunday.

He captioned the photo: 

😭😭😂😂😩😩 HAPPY BIRTHDAY KING‼️ THANK YOU for letting me see what a great Mama you got ! That was the first thing I fell in love with,,, The way she Loves FOR You is something I can't wait for ! Can't wait for the bond I'm going to have with my daughter so Thank You King for allowing me to see that! Everybody Loves You! HAPPY BIRTHDAY WOOHOOOOOO TURN UP ! GO DODGERS