Of all the characters that have become so beloved, so iconic, and who are so unbelievably brilliant at the forefront of the phenomenon that is the Star Wars franchise, there may be none more central or more critical than Anakin Skywalker. The Skywalker Saga may start with his son as the hero, but Anakin and Vader are indeed at the center of it all, creating the history.
When following Star Wars' chronological timeline, through watching Anakin grow up as a slave on Tatooine into a Jedi and then a Sith Lord, there are many ways in which Anakin deteriorates.
Impatience
One of Anakin's most prominent traits that we see him deal with all through the prequels and The Clone Wars is his unbelievable lack of patience.
Rushing into battles, he is not ready for and getting his arm cut off, or believing he needs to be the greatest and most powerful Jedi of all time in his twenties. Anakin's patience is lacking and often gets him in trouble.
Overconfidence
Going hand-in-hand with this lack of patience is Anakin's overconfidence, his overwhelming belief in himself which, at times, is good and lends itself to the situation, but sometimes just comes across as too much.
He believes he can solve any issue by rushing in headfirst with a lightsaber, he sees himself as above Obi-Wan, as above Yoda even as a 'swordsman.' His impatience only serves to encourage his overconfidence, which stays with him until he gets literally dismembered.
Resentment
One of Anakin's biggest struggles, especially when it clashes with the fact he is a Jedi Knight and fully engrained in the Order, is that the man can hold a severe grudge he cannot shake at times.
These are often understandable, such as the Tusken Raiders who kidnapped his mother, or Count Dooku for his part in the war. On top of that, by way of lying to him at times, and their treatment of Ahsoka, as well as their rejection of his status as Jedi Master, the Council bare the weight of Anakin's resentment, even Obi-Wan at times.
Anger
Like his overconfidence and impatience go hand-in-hand, so too does Anakin's resentment towards various people and his undeniable anger that builds and builds.
For three movies and seven seasons, fans bear witness to Anakin's burst of anger, which eventually culminate in his fall to the Dark Side. The Clone Wars adds a lot to this, showing fits of rage from Anakin, and even subtle nods to his anger.
Paranoia
As the Clone War comes to an end, in the years after his mother's death and his inability to save her, Anakin gets very paranoid, specifically about Padmé.
This gets amplified when he loses the person he cares about most, arguably just under Padmé, Ahsoka. In Revenge Of The Sith, Anakin is so desperate to save Padmé from a death he is so sure will happen, it massively aids his fall. On top of that, he also is massively paranoid about the Jedi Council by the end of the movie, even before his fall, believing they do not trust him, which they certainly act like. This joins together and culminates in "you brought him here to kill me."
Jealousy With Padmé
Speaking of his paranoia with Padmé, a similar feeling accumulates throughout The Clone Wars, with hints of it in Attack Of The Clones, that being jealousy.
Anakin does not always believe he will lose Padmé to Rush Clovis, or that she will go back to her past and run into Palo's arms, but he does get insanely jealous. At points he is so overly protective of Padmé when it comes to Rush, it makes you root against him, not for Rush, but Padmé, and against Anakin's toxicity.
Violent Tendencies
Going back to Anakin's revenge against the Tusken Raiders for the murder of his parents, this is just one of many examples of Anakin showing violent tendencies, playing off the anger within him.
Perhaps the most significant non-movie example of these tendencies come in the seventh season of The Clone Wars, where he dismembers and then kills Admiral Trench, exclaiming he does not have the same weaknesses the Jedi abide too. It is something that never ceases, and his violent nature is with him through his time as Anakin, and obviously as Vader.
Internal Struggle
One of the primary features of Anakin that makes him such a fascinating, brilliant, and tragic character is that he is always fighting an internal struggle, a struggle in which the wrong side wins.
He is constantly torn between his duties as a Jedi and his love for Padmé, his want for the war to end and his belief that the Jedi do not have what it takes to finish it, his fear of Padmé's death and his knowing that it could take him down a dark path.
Bottling Up Emotions & Then Letting Them Control Him
This is what the Jedi Council sees as Anakin's most significant issue, the undeniable emotion he has inside of him, that he, on so many occasions, allows to control him.
On this occasion, the Jedi Council's worry is completely one hundred percent justified. Look at the earlier example of Admiral Trench's death, or when Anakin nearly kills Barriss Offee, or when he does kill Count Dooku, or how he reacted to losing R2 (understandable, of course.) Anakin is so often a victim of his emotions, something that, as a Jedi, is not good.
Darth Vader
This is the most obvious way in which Anakin gets worse, he literally falls to the Dark Side of the Force, becoming the most notorious and legendary villain of all time, and the most feared being in the Galaxy.
There were so many factors leading to Anakin's fall to the Dark Side, from his lost faith in the Jedi Council to Sidious' grooming. It all accumulated and resulted in him losing himself, getting covered in an all-black suit, and becoming Darth Vader.