Binary Trojan Horse

Over centuries evolution couldn't keep pace with changes brought about by mankind. Earth deteriorated so that it could not sustain supporting life indefinitely.

In a close region of the galaxy another world had begun to experience a life threatening crisis of their own. Nothing they tried could avert the probably extinction of their civilisation. They listened to creation in the hope that there was other life out there. They heard a greeting from a close neighbour when the Arecibo message arrived in their vicinity. It gave them the only life-line they had.

As a type II civilisation they had evolved past the warlike, aggressive behaviour they observed on Earth. They no longer had weapons of annihilation to use on themselves or anyone else. The initial hope that the message gave them soon disappeared when they realised the impossibility of trying to enlist their neighbour's help. But something had to be done to save their people. Rather than to try and fight them would it possible to make friends with them?  That seemed most unlikely from what they saw of these earthlings' behaviour to another alien species that had tried for thousands of years to establish a mutually beneficial relationship.