Captain America is a symbol of the World War 2 era. Eventually becoming a man lost in time, he continued to inspire characters within the Marvel universe. This legacy extends itself through the Marvel Cinematic Universe and has inspired many heroes and created many villains.
However, after the retirement of Steve Rogers, a new character appeared to take over the mantle: John Walker. A relatively new character to the MCU franchise, many fans are still on the fence about this "Captain America" due to the fact that they don't know much about him. He seems determined to prove that he is worthy of the role in The Falcon & The Winter Soldier, but whether he can remains to be seen. However, if the writers follow a similar story to his arc in the comics, it would be unlikely.
He Was Inspired By His Brother, Not Captain America
Although the character has put on the mantle of Captain America in the past, he wasn't inspired by him. Due to opposing his ideals in the comics, his primary source of inspiration as a soldier was with his brother and father, who he hoped to live up to their names.
Eventually, he got an honorable discharge from the army. However, it is unknown whether this will end up playing a role in the MCU version.
He Is A Member Of Force Works
Despite his personality, the US Agent has proved that he can be a team player as he has been part of several teams before. One of these teams was called Force Works, which had a different outlook from the Avengers.
This team was, somewhat, more proactive when dealing with threats and primarily handled natural and man-made disasters. Although he worked with different iterations of the team, he is regarded as a wildcard by many members.
He Once Wore The Venom Symbiote
During a battle with Nuke, the US Agent was severely injured and ended up losing his left arm and leg. As such, he eventually retired and ended up becoming the warden for the Raft. However, while he and his team were transporting the Dark Avengers into the raft, they were attacked by a group of supervillains, who ended up teleporting them to another Earth.
While he was there, due to a variety of circumstances, Walker was seen to bond with an alternate universe Venom symbiote. Due to its powers, this symbiote was then seen to restore the US Agent of his limbs, which allowed Walker to rejoin the army.
Not As Violent As His Comic Counterpart, Yet
The US Agent in the comics is notorious for his violent and wild stance as a hero. When his family was brutally murdered in the comics, he went out of his way to kill anyone involved, which caused his mental health to decline. Although it doesn't look like he has any violent tendencies in the MCU, it's possible that it can happen soon.
He Used To Be The Super Patriot In The Comics
Unlike the MCU version, who was simply an active soldier before taking on the Captain America mantle, the comics version of the character was originally Super-Patriot. Although compared to his more recognized appearance in the comics, he was only Super-Patriot for a brief time. This persona was meant to put the character on the map before he took over the Captain America mantle. Eventually, he removed himself from that and became recognized as the US Agent.
He Doesn't Have A Wife In The Comics
As shown in the second episode of Falcon & The Winter Soldier, Walker has a wife named Olivia Walker. Comparatively, it is shown in the comics that he doesn't have a wife and is more or less a full-time hero. That being said, having her appear in the MCU potentially adds layers to the character in unique ways. Walker does face a lot of tragedy in the comics so it's possible that she might act as the new catalyst for the character.
In The Comics, He Was Trained By Taskmaster
In the MCU, John Walker was shown to be a highly decorated soldier with three medals of honor. He is an active boxer and can even contend with some members of the Flag Smashers. On top of that, his skills with the shield are impressive.
Although he is a war veteran in the comics, that version of the character also got the chance to train with Taskmaster, a formidable assassin in the Marvel universe. Making him formidable enough to fight and contend with Captain America.
John Walker Has Used Multiple Types Of Shields
As he was Captain America at one point in his career, John Walker is capable of using his iconic shield. However, after his time as Captain America, he eventually started to utilize different shields of all shapes and sizes. This results in him being a master with the weapon (although not as well as Steve Rogers). The MCU shows this skill with the fact that he can use the weapon with ease and has saved his ally Battlestar with it at one point.
He Was Always Meant To Be Manufactured For The Government
The unfortunate reality that has been shown in the MCU is that the character was meant to be a manufactured replacement. Replacing Captain America in order to be used for the government's devices.
This is also shown in the comics during his time as Captain America, where he was selected by the commission. Not only that but by the time he became the US Agent, he was under hypnosis to believe that his parents were alive and gaining a new identity. Although they didn't last long, it's clear that he was only used.
He Became An Avenger
Despite his violent tendencies, John Walker eventually became a member of the Avengers in the comics. Whether or not his MCU counterpart will become one himself remains unknown, however, it does indicate where his allegiance lies.
He may be a violent and brutal character, he still has a belief in good and tries his best against different villains. Showing that the character is more than just a used toy for his country.