The Falcon & The Winter Soldier: 12 Biggest Takeaways From Episode 5
10. John Will Be Back With A Vengeance
Taking the super soldier serum doesn't change much about a person, instead it simply amplifies what they already are inside. Good becomes great, while bad becomes worse. John Walker is most certainly a case of the latter, something that he continued to demonstrate even after he murdered the wrong Flag Smasher.
Even though it was Karli that murdered his best friend, John was still adamant that he did nothing wrong. He felt that he was forced into doing what he did, and that he didn't deserve to be stripped of the Captain America mantle. No one else understands what it takes to be Cap according to John Walker, which may be one of the most infuriatingly ironic quotes in the entire MCU.
John was in no way willing to give up his shield after the incident in Latvia, it had to be forcibly taken from him by Sam and Bucky. Even during this fight, he tried his hardest to kill both of them, proving that there is nothing he won't do to remain as Captain America.
Off the back of Contessa's suggestion, he can be seen in the post credit scene crafting his own shield, signifying that he is not prepared to step away from the mantle. With the super soldier serum running through his veins, John will be looking to prove he can be the one to bring Karli Morgenthau down, regardless of who he has to hurt to do it.