Plot = 8.3: The plot seems to be 'Katara has depression and goes on a journey of self-discovery and realisation to get better ft. religion'. It's certainly interesting, and I haven't seen it before. There's not a lot to say about this section because it is very much a character-based story, not plot. The characters decide what is going to happen to the plot, not the other way around. That being said, there needs to be some actual plot, and thus far it's simply been centred around Katara and her everyday life. There's nothing wrong with this, as such, but without the emotions that come with a depressed character (which I'll talk about further down), it makes it a little difficult to read.
Characterisation = 5.9: This is a story that takes a big, long look at the characters; it's a character, not plot, driven story. And that's fine. However, when taking such liberties, it's important to ensure that the characters are still in-character. Starting the story with depressed!Katara is an interesting way to go, but the readers need to understand exactly what triggered it—or if there even was a trigger. With no explanation at all, it makes it hard to believe int the characters.
The author has justified it somewhat with the idea that Katara's depression is tied to her mother, however there isn't nearly enough exposition to really justify it. We know nothing about her mother or their relationship.
Believability = 5.6: Don't get be wrong, this is an incredibly interesting story that looks into the mechanics of religion and ties them into the Avatar world. The author has obviously taken something that interests them and added it to something else to create the story. However, with the knowledge we've already been given in-canon, it makes this story slightly difficult to believe. We know that there are spirits and that there is reincarnation, so having Katara of all people question it throws the reader off somewhat.
Of course, this is set in a modern world (an mAU) however this aspect is not obvious from the get-go. I usually refrain from reading the mainpage because the story should tell me everything worth knowing, but it wasn't until I had almost finished the first chapter and Anna pulls out an iPhone that it became truly obvious (Aang had mentioned off-hand Toph using a cane earlier, but without explicit AU-verse worldbuilding, it was simply a very confusing throwaway line). The biggest question now is "where does the canon-verse end and the AU one begin?". I don't know, and that is not the answer a reader should be giving. A reader should be able to see the lines.
The depression, frankly, is a little... off. The believability issue for that stems from two things; the reasons for the depression (as I mentioned above), and the other characters' reactions to them. It's little things, like Bato noticing within two seconds of talking to Katara that she's 'depressed' and Aang not really noticing. The fact that she was put onto drugs almost straight away and that Sokka suggested an 'intervention' also seems to be pushing the boundaries; usually they try not to put someone suffering depression on drugs straight away. Therapy sessions and other activities, like getting exercise, come first. Then there's the added confusion when Zuko, apparently randomly, pipes up and says 'you're not depressed'. This is unnecessarily confusing for the readers, and it doubts the veracity of Katara's 'depression'. Then, there are other moments; in the latest chapter, Bato asks "So then why do you sound like you're depressed?". Depression doesn't magically go away because someone has found the 'answer' to it. It's a chemical imbalance in the brain, and until that's sorted out, any reprieve will be short-term at best. For Bato to say something so callous is incredibly infuriating. Then there is Katara's moment in the latest chapter of "is the depression back"; I don't believe it ever 'left', and as of that moment, Katara is basically pegging on religion to 'cure' her. She over-reacts, as does everyone in the story when it comes to her depression, and it is not accurate.
Technical writing = 6.7: There were several mis-formatted paragraphs, such as neglecting to put a new speaker on a new line. This isn't a massive issue because it is fairly obvious who is speaking once the tags (ie. '[name] said'); however by keeping several speakers in the same paragraph, it goes against the general rule of English and if those tags aren't added, it causes unnecessary confusion and frustration on part of the reader.
Another thing I noticed was the oft-misspelled word; 'hallow' instead of 'hollow' in the first chapter (and then misspelled again in chapter 4 as 'hallo'), and 'lend', not 'leaned' in the second. This is frequent, with usually more than a dozen each chapter. There are also several missing apostrophes to indicate contractions; 'lets' is a completely different word to 'let's' (eg. He lets me go out at night vs. Let's go find a seat). There also seems to be several missing ending speech marks that trip up the readers because they don't realise that the character has finished talking.
Non-technical writing = 6.8:I'm going to be talking about the emotions in the story in this section. Due to being a character-driven story, this focusses less on what happens, and more on how the characters react to it happening. I'm not getting any emotional direction at all. We have no idea how Katara feels—the readers are having the word 'depressed' thrown at them every chapter, but what does that mean? What motivates Katara to just 'convert'? Does she actually believe or is she only doing something because she wants it to work?
Organisation = 8.1: There's not a lot to say about the organisation. The time-frames seem far too short—from Katara needing help to being put on drugs, the drugs 'failing' and then converting to Christianity. Other than that, the chapters themselves flow well enough, and it's easy to see where the story is going.
Total score = 6.9
My advice: This story is rather melodramatic without really showing the reason why. It's about depression and religion, but the readers don't feel anything of the former, and the latter isn't really justified in the sense I feel the author is going for; finding religion can help you deal with many problems and issues in ones life. That's all well and good, but with the lack of exposition given, it moves too fast without giving people the chance to sink into the story and believe in it. I won't way that it takes longer than the time frame given to convert to a religion, but I will say that with the lack of explanation into Katara's thoughts and motives, we don't understand why. My advice is to read over the story and fix up the spelling errors outlined above, but also add more information and emotion. You want the readers to feel what Katara is feeling; at the moment, we're not. We can see she's 'depressed' because everyone keeps saying she is, but it's like watching your friends eat a chocolate bar and describing how it tastes. You can imagine, and you can wonder, but it's all just opinion and hearsay because it's biased with your friend's own point of view.
Why I enjoyed this story: The idea of religion + Avatar is not one I've seen before, and is certainly the selling point of this story. Religion has always fascinated me, and I'd love to see it explored further.