A good story is one in which the main character undergoes some changes. This character needs to learn life lessons, meet new people, gain new skills, get a new perspective on the world, and a whole lot more. Such a change is usually positive, and side characters and villains can undergo such changes, too. A dynamic character is usually a highly compelling one.
This is true of many of the MCU's characters, too, and even the mighty, near-immortal Thor, son of Odin, has had his fair share of change. He's hardly the same warrior as he was from his first appearance, though not everything is different. Thor is still true to himself, but he's done some growing up since he first showed up. Let's review.
10 Same: Defending Asgard
Thor was born in Asgard, and he is 100% loyal to this world and its people. And even after Asgard was destroyed at the end of Thor: Ragnarok, Thor is fiercely protective of his countrymen. He urgently wants to find them a new home.
It's highly commendable that Thor looks out for the Asgardians and their home, and better yet, he doesn't have much of a sense of superiority about it, either. He loves his people, but not at the expense of other worlds and races.
9 Changed: Real Team Player
While it's true that Thor had a band of merry fighters during his Asgard days, the Avengers was the first major fighting force that he became a part of. At first, he struggled to integrate with them, and he butted heads with Iron Man and Captain America early in The Avengers.
But now Thor is a seamless part of the Avengers, and they can count on him during a fight, and vice versa. His combination of hammer strikes, lightning blasts, and incredible strength flows well with the other Avengers. It's great to see him get along with others now.
8 Same: Loves Beer
This is a pretty minor detail, but sometimes, it's the small things that help round out a character. Thor and the Asgardians are based on real-life Viking folklore, and everyone knows that they love a good tankard of grog.
Thor doesn't mind downing a few drinks with each meal, and it's a good way to unwind after a hard day's fight. When he met Dr. Strange, he wasn't in the mood for tea, so Dr. Strange gave him a huge glass of beer out of nowhere (no tip necessary).
7 Changed: His Relationship To Loki
This might be the best part of Thor's character, and one of the best parts of the MCU so far: the relationship between these two brothers. At first, Thor was leery of Loki, and they were downright enemies in The Avengers. Loki was certainly up to no good.
But partway through Thor: The Dark World, their relationship began to heal, and this continued into Thor: Ragnarok. When Thanos killed Loki, Thor was outraged, and he swore that he would take Thanos' own life in revenge.
6 Same: Loves Jane Foster
In real-life Viking lore, Thor is married to Sif, and while Sif appears for a bit in Thor, she is a friend, not a lover. Instead, Thor's heart belongs to Jane Foster, and this has been true since partway through the first Thor movie.
Jane isn't an Asgardian, but she is smart and brave, and she's perfectly ready to help save the entire world. Thor is enchanted by her, and he's even brought her to Asgard once or twice. She's a bright spot in Thor's troubled life for sure.
5 Changed: Lightning Affinity
Thor is the god of thunder, and he has always known it. He can channel that lightning through Mjolnir, his hammer, and zap targets from afar. But early on, he had a distinct preference for striking with his hammer, and he made limited use of lightning.
When Mjolnir was shattered in Thor: Ragnarok, Thor realized that the hammer was just a tool, and his lightning powers were taken to the next level. As Odin said, Thor is the god of thunder, not the god of hammers.
4 Same: Incredible Strength
All members of the Avengers are superpowered somehow, from Iron Man's high-tech suits to Captain America's indestructible shield to Hawkeye's incredible aim. Thor, like the Hulk, has massive strength, and lightning powers on top of that.
Some of the Avengers suffer a period where their powers have failed them, such as Ant-Man and Iron Man. But not Thor; he is always mighty, and even if he's discouraged or afraid, his powers are ready, and he just needs a pep talk to get back into the action.
3 Changed: Likes The Human World
Thor never hated Earth or humanity, and he never harbored any xenophobic feelings. But up to a point, he had little interest in Midgard (what he calls Earth), and he would rather stay on Asgard where everyone is more like him.
But Thor ends up on Earth against his will, and he learns that humanity is actually quite noble and brave, and he has embraced many aspects of Earth life, from modern clothes to PlayStation.
2 Same: Loves His Parents
Thor has always had a good relationship with his parents Odin and Hela, and he only raged against Odin due to an argument over Thor's handling of the Frost Giants. No matter what, Thor honors and loves his parents, and he holds them in the highest esteem.
He and Loki were heartbroken when Odin passed on, and he was moved to tears when he went back in time during Avenger: Endgame and met Hela on Asgard before it was destroyed. He will always remember both of them fondly.
1 Changed: Better Humor
Thor is looking pretty serious in this image, but he only makes that face to his enemies, not to everyone. At first, Thor took himself a bit too seriously, and lashed out against anyone who made fun of him. He wasn't easy to get along with.
Later on, Thor became a much more charming fellow, who is willing to make self-deprecating comments and see the funny side in things. That makes him much more likable, and he was downright hilarious during Thor: Ragnarok.