(semi)Static IPv6 for AWS.

EIP does not support IPv6, but you can still do it as long as you don't delete you VPC or make changes to your subnet.

In the Interface page of your EC2 instance, there's an option to add more IPv6 address (like you can do with IPv4 address); in fact, there maybe a default IPv6 address depending on if you opted for one.

You just add an IPv6 address to the interface -- you'll have control over it, you can remove it from one instance attach it to another (but only in the same subnet).