Alex definitely feels tied to Mars, he has family back there, he grew up there and loves it.
Being from Mars, Alex certainly has reason enough to want to see his family and the people of the planet safe and perhaps victorious in the ongoing war with Earth.
But is the pull of his home planet enough to make him turn on James, Amos, Naomi, and now Prax?
The planet, to him, was always this altruistic force that would never do any harm.