After much philosophy, I've come to believe that heroes need three prime things.
The hero must change throughout the story. They must learn something, overcome their fears, become a better person, or something like that. Without this development, the story feels meaningless.
You want your audience to love and root for your hero. There are two main ways to accomplish this: make them virtuous, or make them mistreated or unfortunate - we either admire the hero or sympathize with them. Usually you want to do some of both.
Also of note, though, is that giving the hero too much credit or glorification actually hurts their lovability severely. I think it's a form of reactance bias: if the story is pushing on us the idea that this character is cool or right more so than we think they are, it makes us dislike them even more.
A person old enough to be a POV character didn't just get born. They have a past. What is it? Of course this is less relevant with child protagonists, but especially with adult protagonists you need to explain how they got where they are in life now. This is arguably the least important area, but an interesting past can go a long way in explaining someone's personality, providing plot material, and making them more relatable.
Luke starts out as a farmhand aspiring to go join the rebellion and fight the evil empire and ends up as an experienced Jedi who has faced his destiny. On the outside, the development is severe, but what has he gained as a person? Maturity and confidence, I'd say, except that he wasn't really shown lacking those things early in the story. He never once displayed feelings of insecurity, fear of battle, or difficulty dealing with the sacrifices that come with war, such as the death of his mentor. This failure to show his need for development in the first place makes us feel that he didn't actually learn much. I give him a 2.
Well, he's risking his life in a fight against tyranny, so there's no denying he's the goodguy here. And he never really does anything despicable. On the other hand, the main virtue he exhibits is courage, but the fear that the heroes of Star Wars would be facing in the situations they're in is never mentioned or acted on by anyone, which makes the courage that he exhibits seem less admirable (this is the example I was talking about). He also has a very low sympathy factor. Sure he loses his parents and his mentor but he gets over both so fast that it completely kills whatever emotional impact there would have been (not to mention how he wanted to leave his parents anyway). Still, I'll give him a 3.
None. 2 points instead of 0 because he's a borderline child character - he's just been living at home with his foster parents the whole time, so he has an excuse for not having much of a past.
Anakin does pretty good on this. He has a strong inner conflict that is consistent throughout both the movies he's the protagonist of: he is torn between his vow of celibacy and his love for Padme. Revealed in the beginning, resolved in the end - that's the way it's supposed to be. It still could have been fleshed out more, but overall it was decent. 4 on this.
Like Luke, he's a brave Jedi fighting for the republic. Nevertheless, the politics of the war are mostly hidden from us, so it's harder to tell which side is which than it should be. It really hurt his lovability when he complained about not getting the rank of master. Getting put on the council should have been more than enough for him. In his defense, he's in a bit of a sympathizable position what with being ordered by the Jedi council to spy on his friend and then when he makes the decision to report Palpatine to Mace Windu he is told to sit the confrontation out - an insulting breach of trust that makes us able to see Anakin as the goodguy for a little bit longer even after he turns to the dark side. I'm going to end up giving him a 3.
We know a good bit about his past from The Phantom Menace. Not only how he lived his childhood as a slave, but we know he built C3P0, which is a great example of using a character's background to relate to the rest of the cast. We also know he spent the interim training to be a Jedi. Unfortunately, we don't really know what training to be a Jedi entails. I'll give him a 5 - would have been an easy 6 if we knew more about what he did between TPM and AOTC.
Her abusive brother Reen has taught her that altruism doesn't exist and life is just about exploiting other people as necessary to survive. Her arc is about overcoming this attitude, which she does in the end of the book. Revealed in the beginning, resolved in the end - beautiful. 6 points!
She's had a shitty past full of both physical and emotional abuse that gives her a strong sympathy factor to make up for her lack of admirability (kind of the opposite of Luke). There was one scene, though, that really damaged my opinion of her, which was the scene where Kelsier saved the Skaa prisoners and Elend, fighting tons of soldiers and even an Inquisitor by himself while Vin did nothing. As if she wasn't already lacking in agency... 3 points.
We know she's lived as a member of various thieving crews her whole life, barely surviving, and we know what happened with Reen and all. For a child character, it's as deep past as we could have asked for - 6 points.
Kaim knows he is immortal and has lost his memories. He starts out having no purpose and nothing in the world that he cares about - he's learned to stop getting into relationships because he knows everyone but him will die and he'll spend much longer missing them than he did knowing them. He says he doesn't even want to remember his past because he thinks it probably didn't amount to much. His arc is about coming to terms with living among mortals and caring about them. It's a beautiful theme for a story, especially given its significance to Protagonism, and not one that is overdone. The pinnacle of his is arc is incredibly satisfying: He remembers the mission for which he was sent into this world and made immortal, and has the option to complete it and go back to his native world, but he chooses to destroy his way back instead to save the mortals. 6 points.
Not great. He's extremely brave, but kind of an asshole - he chokes Jansen just for following him and never apologizes for it. Nevertheless, later in the story he demonstrates that he does care about people besides himself. He surrenders to Kakanas in Numara to avoid triggering a war, and sacrifices himself (sort of) to save his grandchildren in the snowstorm. 3 points.
Excellent. We know tons about him from his Dreams. We really couldn't have asked for any more. 6 points.
In the beginning he is a selfish coward. Throughout the story, he primarily gains courage, but also learns to see things from others' perspectives a little better. For example, when he first finds out what Katherine did to David to make him overcome his phobia, he is furious with her, but later in the story he comes to understand that she really did mean well, even if he doesn't agree with that particular action, and learns to respect her for being a good person in her own way. Both are very believable because he learns from the examples of those around him. The only major flaw with his arc is that in retrospect it seemed like it was kind of resolved in chapter 3, so I think I ended up sort of downplaying the permanent effect that such a chapter would have had on his soul so that he would still have ground to cover later on, and in the end of the book when he finishes becoming braver it seemed like it came out of nowhere. This prevents me from giving him 6 points, but I think 5 is still justifiable.
He's a jerk in the beginning, but soon gets better. And he's being compared to an enemy about as evil as Mistborn's enemy (not Rashek, but the Final Empire in general). He also has become quite brave by the ending, balancing out the teams to his own disadvantage during the penultimate battle and volunteering for the role where he collapses the ceiling. Again, though, there's that sympathy factor which is completely missing. He has a great life compared to everyone else on Team Good. 3 points.
Unfortunately for me Jaydin has essentially no history. The reason is because I wrote this back before I got creative, so the only type of protagonist I could think of was, superficially, a copy of me: a teenage boy who lives with his parents and has no past worth telling. I'll give him 3 instead of Luke's 2, because he's younger and so his excuse of being a child character is stronger.
The reason agency isn't on the list is because I consider it rather a responsibility of the plot.
Note that believability is not on the list, despite seeming like an obvious candidate. I thought it was for a while. Then I decided that it could be reduced to the other three and/or to the plot. A character who is believable in general but acts out of character in a scene I would say is a perfectly fine character, the problem is with that scene. A character whose fundamental traits are inconsistent or unrealistic I would most likely consider to have a bad arc, since a strong and satisfying arc cannot exist if the character's problem that sparks it or their solution to it is unbelievable. If the way they're unbelievable is by seeming unaffected by things such as fear and pain (we'll see an example of this down below), then I would count that as a strike against their lovability, since that makes what would otherwise be an admirable person into a less admirable person.
Anyway, I'll now analyze some protagonists of popular stories and give them ratings in each area. The scale is 0-6.
Luke scores an average of 2.33 over the three areas. Not good by any means, but acceptable.
(He wasn't the protagonist of the first movie he was in, so I'll only consider the second two.)
Anakin scores an average of 4.0 - much better than Luke. That's actually a pretty good score.
(I'd love to put Rey on here, but I feel I don't remember enough of what happens in The Force Awakens to be qualified to judge her.)
(I'd also like to have Frodo and Harry Potter, but can't for the same reason)
Now some less popular stories that I've seen.
Vin (from Mistborn: The Final Empire)
(I'll only consider the first book of the series, because it was the only good one.)
Vin's overall score: 5.0 - an excellent score.
Kaim Argonar (from Lost Odyssey)
Kaim's overall score: 5.0. Another excellent score.
And now some of my stories.
Jaydin (from Pillars Of Life)
Overall rating: 3.33.