This isn't bad, exactly, but if you're intending to write again, I suggest that you work harder on your characterization. Your Harry Dresden just does not sound like Harry Dresden. The underlying, defining voice that makes you able to tell which character is narrating any given part of a story just by how they look at things, phrase things, think about things, all that is just a little bit off. Consider doing exercises like taking a random scene from a novel and re-writing it so that it is told from the perspective of all the characters taking part in it, and then make each of them sound as distinct and unique as possible. It's difficult, but you'll notice the difference the moment you pick up on how to do it right.

Schöne Grüße aus Freiburg.

I looked it up...I've watched an entire compliation of people sweezing these out aready

I do really like this story, and it is nice. My only problem is that Frisk is ordinary. I know, you've got a reason, and a good one at that, for it. But Frisk did more then just go back in time. Like you even point out in the story they flat out beat Undyne in her super mode to boot. In the pacifist route they have the Determination to tank Asriel's super laser without dying. Not to mention the whole 'refusing to die' thing.

Greatly enjoyed, excited for part 2!

Excellently finished, good sir. A solid addition to the Dresden Files fandom. I tip my hat to you and look forward to more of your works in the future.

All good things come to an end, huh... But yes, this really does leave room for a very intriguing part 2, waiting for that with interest.
Anyways, this was a wonderful conclusion to this story! You got both Morgan and the Merlin, as well as the whole trial, down to a t. Figures Merlin would have tried to find a way to pin at least something on Harry. Also, have to give to Asgore for what he did in the end, that was respectable. Congrats on finishing your first fic!
...still chuckling at Sans' "spell it out" pun. xD

Yeah... It's things like the last chapter which make me think that the White Council really isn't all that different from the other supernatural groups. The whole "for the greater good" sounds alright on paper, but it's just so dang easy to shift the lines for convenience when the people in charge are greedy and petty.

I will say that what Asgore did was at least respectable, he helped his people and found a way to punish himself for his past actions. It's not often someone is willing to truly face the repercussions for what they've done. Frisk would also fall into that category I guess. They tried to take the blame and be punished but weren't. Though as Dresden said, that'll probably change once they start telling the other monsters the truth.

Gotta say, thanks for the entertainment. This story has been a blast. :D

Cannot wait for part two!

A delightful conclusion to a wonderful story. I'm glad to have read it. Thank you for taking the time and putting in the effort required to build this gem.

Gah, I shouldn't have read this chapter as I can't finish reading this fic now, but couldn't resist. Bugger, I want to read the rest too right away... oh well. at least I know what I'll be doing tomorrow night.
Btw, one little thing, and I might be wrong, but I would say that when you're using 'they' to refer to a single person, as in the case of Frisk, you should say themself, not themselves. They have only one self, anyway... (I think it's that way with the royal we too: "we ourself".)

This was great! Eagerly looking forward to whatever you do next. :)

Excellent work. I enjoyed that a lot. I look forward to the sequel.

You know, I would all be for redeeming Chara. I could buy that. I really could because all the damage that was done was basically undone because everyone was brought back to life. However, two children are dead. Chara killed two children. I fully agree and feel Harry's frustration right now because those two kids aren't coming back. If that was your intention as to feel Harry's emotions, it's done well. So far, Chara has crossed the line. I stand with Harry and Flowey right now.

That being said, this is a really great fic. While I only recently got into the Dresden Files and only know a smidgen of Undertale lore, this is done in a believable and in character way that I can't help but love it. I adore the interactions and how the characters play off each other. Brilliant work thus far and I can't wait to read more.

Jesus christ, you know shit has gone pear-shaped when Flowy is the logical one.

These chapters were a real ride! I kind of feel like I just keep on saying it chapter after chapter, but I'm really eager to see how this'll turn out. Getting from one delightful mess to another, aren't they.

Random thoughts:
Using Dresden soul for tracking is just kind of ingenious. Totally crazy too, but igenious.
And I kind of knew not all the kids would make it, when that boy (Corbyn?) said children don't die in these things.
Poor Michael. xD I feel for him. "Am I hearing this right?" must be a question on his mind all the time.
This last chapter I didn't have time for any random thoughts. Did I already mention I'm eager to see how this'll end? What they'll do with Chara? How they'll deal with the parasites? Will monsters and humans make contact? What will the council say of all this? Too many questions!

(One little thing, should it be "reality doesn't work like that" - "if it DID, prisons..." and not didn't?)