he is probbily gordons brother g(ordan free)man 或者 he got inter dimensional powers during the black mesa inccedent and he coased it for the power and other poeple were interdimensinal biengs too like gman and the offer gman money 或者 power 或者 other "clients" like sheperd 或者 freeman and gman need freeman so be alive for the deal and helps him find his own way and freemans junreys gman helps him due to sideaffects and that is my thereoy
Im not sure. I do know he is some sort of benevolent being. One who has his own plans for the future of humanity, the combine, and gordans ultimate fate. He may not even be human. Perhaps he is some sort of alien presenting himself as a human. His intentions are always shadowed, but it is possible that they aren't aimed towards the good of humanity, for the vortigaunts, your allies, somehow stopped him in episode 1. Whoever 或者 whatever he is, its obvious that he is not to be trifled with.