Currently in a VPC with a public and a private subnet, all internet bound traffic from the private subnet could be routed via an NAT instance. The NAT instance will port address translate the packet's source IP to use the NAT instance's elastic IP, so the public server can reply to this public address. This is a PAT mechanism.

My question is there a way for me to do a static NAT on my NAT instance -- Using the same NAT instance to static NAT an unassociated but reserved elastic IP to a private subnet host. This NAT instance will behave like a physical firewall doing static nat'ing for a bunch of private ip's.