Spain tries his best to ignore Antonio and mostly succeed but there are those rare occasions where he breaks down when he's alone, screaming for it to go away. Antonio refuse though. He wants control and plans on getting it sooner or later.
Antonio isn't necessarily a pirate/conquistador. Spain gave him the nickname Captain Antonio because he acts as such when Spain was a pirate/conquistador. He was also made into existence from these days. Antonio is his dark side that he tries to keep locked up inside.
Spain likes to keep Antonio a secret from everyone. He doesn't want to be called crazy if he told everyone he had a voice in his head. He prefers to be at home instead of a loonybin thank you. It is difficult sometimes and he wants some help but he doesn't want to risk it.
Antonio is most active when England, Turkey, or many others are near. His voice becomes louder and more commanding. He sees them as the cause of most of their problems in their life. He wish Spain would just give into him and kill them already.