Harry states I believe that after Susan was half turned and went away that he was never able to capture sunshine in a hanky again. 
 It has more to do with his own emotional state, which though he is more at peace now, the unhappiness remains, than any floodgates he opened.

yoooi seriously, stip repeating exactly whf I just said likewise just didn't day it. Avoid me Mira. Periomd.  Not to day
Your literally repeating me word for word. Look I get it, double empathy your allistic and just don't understand how I think. I understand you just fine though. Atop replying to me, you literally repeat exactly what I said, an then someone will reply to you instead of me.
Might take other people longer, but I always see. See?

I always figured it had to do with alignment actually... not necessarily DnD style but that's a good marker because it involves multiple concepts.
Harry's Magical alignment varies throughout his career changing as he does in his style of usage. What I mean is, say SF he clearly gets a lightning motif, changing more fiery by GP,(let's see...) he gets more force magic in after the flamethrower, he'll fire from lasciel, ice from WK mantle, ect.
One caveat of magic(which just now I'm seeing a huge.. flaw? In harry being winter knight) is you are what you do and the more you do it the more it defines you.
Harry's motif in GP was fire, more so BECAUSE of the scene and it's related emotional response I think
Pyro fuego pyro. Can be translated with his intentions to do more. Say, HOT PASSION FIRE.(where were his other usages of it? We're they always a charged situation?)
He more or less, charged his magic with, himself, his soulfire. Uriel said he made him more of what he already was. I supposite, wizards can always use soulfire, the throwing of themselves into their spell completely.. but either by design or by concealment they weren't aware or couldn't break of that energy piecemeal, to access it is to throw the whole bottle..(which yes, I think does imply death curse wizards burn themselves into it)
An what Harry did might have been different because of his intentions, he didn't try to throw a death curse, he didn't intend to die an maybe, because he wasn't acting on instincts of destruction, it was in fact an example of the fabled opposite of a death curse, one born with intentions to create..
That he created destructive fire, is exactly why he was so torn by it. He had total control of it, it didn't burn him. The only other case we've seen of this is Justin which seemed to imply it was a matter more of control and belief(the two going hand in hand). The hardest part seemingly believing the disconnect from reality that is fire burns you.
Makes me wonder about 1 if NN domains can be so foreign because the owners idea of reality matches, al la Mab.
And 2 if Harry's immunity there isn't indicative of his position as a purifier(the nice way bad people say we're gonna destroy you lol), an agent of change and chaos.
Divergent thought... As far as the starborn aspect? Can't protect from yourself.. which is telling to me. He's a child of the stars and he specifically can effect outsiders because of this. The NN physically goes around the planet to about the moon per woj,  so where are the stars? And what does being born to them have to do with outsiders?  Is it the stars that we need look at, or the spaces between them..

Harry has chosen his path, no one walked it for him

I could say much on this topic, I have a fairly evolved tree of theory on it. But my idea for dresden isn't that he's a new being.. but a new identity for an older group of archetypes. A swirl, the easiest I think to see is the similarity of the 7 sins an seven laws. They are unbalanced. Twc's forgiveness saves from sin, but harry... isn't so nice. He'll be more weighty in his jurisdiction.
The above quote sparks such a parallel to Nic saying he is his path... Harry is the one who's really like that. Even with possible TT shenanigans, he's just manipulating his own circumstances to make better choices..

Before-and-after, for Merlin, is virtually impossible to determine from our information.

it also occurs to me that we don't know if the original merlin... was originally named Merlin. Could be a late game identity (I've always thought so, mostly because I became a role)
Just linearly,  he could have passed time in the NN.. do we know when the white council was actually created? I can't remember any hard evidence other than when Edinburgh was won, is anything before that simply conjecture based on the age of the oldest known wizard ie gatekeeper?

So are you saying that Jim stole the idea from Star Wars?

pointing out the loosest of tropes existing elsewhere is not 'stealing'. Honestly, the things people focus on...

Even if he did, Harry was born before the prequels to the original Star Wars trilby came out, the first one 1999.  So yeah, possible, but at the same time unlikely.  Just as likely that Malcolm a vanilla human stage magician would name his son after a well known and I imagine admired stage magicians, Harry Houdini and David Copperfield.  In fact I believe Harry said that back in Storm Front.. Now Malcolm could have lied to him about that, but what would be the point.

Harry the unreliable narrator with a very confusing backstory even without the constant shifts?
Let's jump back to Star wars for the metaphor of chosen Orphan. Did luke know... Anything that was true? Leia what about Rey?
I find it far more likely they named him together, as they were indeed together before her death 👀
I find it fair less likely Malcolm named him unilaterally and just by happenstance gave him the extra protection of names in a verse where such things actually matter.(Something Harry mentioned in storm front, FM, GP, ECT)
I also find it fair more likely anything i say would be disagreed with lmao. I wish when people did that they'd see just how untenable their opinion quickly becomes. Lotta extra waffle when,' i personally disagree" would do just as well.

I'd think that:

• if Harry&co could prove that Nemesis was actually the bad actor
• if the Svartalves know of Nemesis

then Thomas could escape the most-severe Svartalven penalties.

But I'm not at all confident that (in Jim's Dresdenverse) this is the case.

through might or right, Thomas can't come back without doing so on some level tho.
Skipping out of the grave sword in hand just to be throttled by a svartalf would definitely subvert expectations...

He just decided NOT to ever finish the DF citing that he's sick of people questioning wether he'll finish it at all he's decided this is the only way to give a definitive answer 😞
😄 On the bright side head canon just became the only Canon 🤣