WARNING: The following contains spoilers for King in Black Captain America #1 by Danny Lore, Mirko Colak, Stefano Landini, Rogê Antônio, Nico Leon, Erick Arciniega, & VC's Joe Caramagna, and recent issues of Avengers by Jason Aaron, Javier Garron, David Curiel, and VC's Cory Petit, both on sale now.
Cosmic forces have been hitting the Marvel universe in abundance with both King in Black and the "Enter the Phoenix" story arc currently taking place in Avengers. In one series the Avengers have been battling against each other in a tournament hosted by the Phoenix Force, as the fiery space bird tries to find a new Earth avatar. Meanwhile, Knull has arrived with his symbiote army to take over the entire planet. What do these god-like creatures have in common? They both want to possess the Star Spangled Man with a Plan - Captain America. As a symbol of justice and hope, Captain America would be a key instrument for any invading force attempting to take control of the planet.
Steve Rogers, more famously known as Captain America, has always known who he is. He was originally a skinny kid from Brooklyn who never stopped fighting for what was right, even to his own detriment. It was because of his spirit and good heart that he was chosen for the Super Soldier experiment that turned him into Captain America. Through the years he never lost that drive to stand up for the little guy, even going against the government on several occasions to do what he felt was right. However, his self-identity and core beliefs about himself were altered after the events of Secret Empire when a fascist, Hydra-loyal version of himself took over his life. Since then he has gone through several instances of self-doubt. Now, with two cosmic forces trying to take over his body, Captain America has been questioning his worth and merit more than ever.
In Avengers #40, Captain America appeared as the first hero the Phoenix possessed. Brought back to Earth by the call of Namor, who wanted to use the entity to destroy all the land dwellers, the Phoenix brought both heroes and villains to vie for her powers. Pitted against Doctor Doom, who was ready to embrace the Phoenix, Captain America knew he didn't want the power but knew that Doom shouldn't have it either so he let the fiery power in. When the Phoenix entered him, Cap questioned what would happen to him -- to the real Steve Rogers -- if he let the force take him over. In the Phoenix he would be lost, and only the fiery presence of the Phoenix would remain.
Contrasting the brightness of the Phoenix, there is the dark all-encompassing power of Knull. The King in Black hit New York City and spread his symbiotes over everything he could reach. As part of the defensive line against this creature, Captain America was on the ground when the symbiote goo took him over and enfolded him into Knull's army. Before he was absorbed, he did not have time to question his place in the universe. In one moment he was the Sentinel of Liberty, and in the next he was an extension of Knull. After he was freed by Venom's son Dylan, Captain America didn't take a break to recover. He immediately went back into the fight, convinced that he would never give in to Knull's pull again.
In both battles against forces greater than himself, Captain America questioned his self-worth and value to the world. Yet, against the Phoenix and Knull, he was able to break free from the pull of the abyss. Against the Phoenix he connected back to his true self, the skinny kid who never knows when to quit, and not the icon everyone turns to. Even though he was losing against Doctor Doom, when he got up and said through blood on his face that he could "do this all day" he won the battle.
Against Knull, Bucky Barnes and Sam Wilson saved Cap from himself. They reminded him that he was only human but always made decisions in the best interest of others, that is why they love him. Knowing that he can stumble and still get back up, to always fight for people who can't save themselves, is what keeps Steve Rogers going. As much as Knull and Phoenix want to possess that symbol, Captain America is not so easily taken.