Marco wasn't too keen on Ava's presence when she first arrived but after realizing a few weeks in that she was here to stay, his attitude towards her changed and he became her protector!  Anytime Ava would be crying Marco walked over to her to make sure she was alright and ensure we would tend to her needs.  This happened all through her toddler and preschool years.  As Ava got older and would not be at home for longer periods of time, the smile on Marco's face when she returned home was so heartwarming.  Most recently, when he realized she wasn't around after leaving for college, Marco slept in Ava's bed for a few nights showing, without any words, just how much he missed his baby sister.  His love for her is incredible!