Asian Water Monitor

We were having a swim and suddenly I saw something move at the surface of the water near the edge of the pool. I first though it was a bird, but then I saw it flicking its tongue. It slowly moved out of the pool and when I got distracted by a movement on my other side (there was one more lizard in the water, a tiny baby see spotting http://www.projectnoah.org/spottings/2102176003) this one slipped out and slowly walked towards the showers, where it sat in the sun to dry. I ran home to get my phone but when I returned he already disappeared into the undergrowth. I did manage to take this picture a bit later went I went looking for him again. He was happily munching away on stuff Asian Water Monitors munch on.

Looking on line it seems that the other one is a day old hatchling! Now I wonder what their relationship is. This one is slightly bigger but not big enough to be the parent. Could it be an older brother/sister??? Anyone?