Here is my best shot at it. I added another Div and made it red and changed you parent's height to 200px just to test it. The idea is the the child now becomes the grandchild and the parent becomes the grandparent. So the parent respects its parent. Hope you get my idea.
<html>
<body>
<div style="background-color: blue; padding: 10px; position: relative; height: 200px;">
<div style="background-color: red; position: relative; height: 100%;">
<div style="background-color: gray; position: absolute; left: 0px; right: 0px;bottom: 0px;">css sux</div>
</div>
</div>
</body>
</html>
Edit:
I think what you are trying to do can't be done. Absolute position means that you are going to give it co-ordinates it must honor. What if the parent has a padding of 5px. And you absolutely position the child at top: -5px; left: -5px. How is it suppose to honor the parent and you at the same time??
My solution
If you want it to honor the parent, don't absolutely position it then.