In the prologue, Arikado notes that because Soma wasn't in danger for a long period of time, his Power of Dominance became dormant, causing all of the souls he absorbed to be released. This would explain why enemies killed in Aria of Sorrow (such as Balore) are alive and kicking.
Julius is a strange choice for an on-deck Soma/Mina shipper... Wait, he probably knows Dracula has a history of being driven to evil by losing loved ones. He probably wants Soma to have a happy ending so that evil never resurfaces, as well as because they're such good friends. (Indeed, the worst ending can be triggered by Soma witnessing the apparent death of Mina.)
You can find Excalibur, though it is rather humorously still stuck in the stone, since Soma isn't a reincarnation of King Arthur, but of Dracula.
When playing Dawn of Sorrow, this Troper noticed that in order to get most of the Souls in the game more powerful, you need to own more copies of it to use them at their full potential. This somewhat contradicts Aria of Sorrow, where Soma only needs one copy of a soul to get its full power. However, consider the difference of location in the games. In Aria, you're going through Castlevania, the domicile of Dracula himself (who Soma is a reincarnation of), whereas in Dawn, you're going through a mere replica. Maybe the reason that Soma needs more Souls for more power in Dawn is because he's not somewhere he's inherently connected to his power/castle.
On a semi-related note: Dawn is more user-friendly than Aria. Aria doesn't tell the player how to use souls in combat, but Dawn has a tutorial that shows what kinds of souls there are and which buttons to press. Soma's just figuring out his powers in Aria, and knows exactly how to use them by Dawn.
It could work the other way around as well. In Aria, Soma was in Castlevania, his previous life's and technically his own domain. A tutorial wasn't present because it's much easier for him to know how to do things without needing to really think about it because he's in his home territory. In Dawn, Soma has to relearn how to use his powers because he's outside of a place where he could easily use them, and thus not instantly knowing how they work. He does mention that he's lost the ability to use any souls he had, and Arikado further expands saying the power went dormant because he wasn't in danger at all, thus making him lose all his souls and knowledge of how to use it as well.
All four of the Dark Lord candidates from Aria of Sorrow and Dawn of Sorrow have something in common with Dracula in addition to their powers.
Graham has his One-Winged Angel form (technically Menace is Dmitrii's, but that was unintentional, uncontrollable, and required Soma's power), but also Dracula's ability to attract cults.
Dario has Dracula's affinity for fire, in addition to his anger issues.
Dmitrii's copy ability is like the poor man's substitute for Dominance. His ability to manipulate events when he doesn't even appear in the picture is similar to Mathias manipulating Leon.
Soma has Dracula's Power of Dominance, aka the power to "Steal men's souls and make them [his] slaves", as well as being Dracula's true reincarnation. It's worth mentioning that Soma is a normal human being who gained supernatural powers upon taking in monsters souls, much like how Mathias Cronqvist, the man who would become Dracula, originally had to take the soul of Walter Bernhart into the Crimson Stone to become a Vampire himself. Like Mathias pre-Face–Heel Turn, Soma is a good person and remains so while Mina is alive and well, but can easily fall back into evil should the object of his love die, much like how Mathias decided to Rage Against the Heavens in the form of Dracula upon Elisabetha's death. In short, Soma is very much like pre-Dracula Mathias.
A bit of Fridge Brilliance this Troper ran into when replaying Dawn of Sorrow. After you beat Dmitrii and he seemingly dies, if you return into his room later, you'll find it's inhabited by a Quetzocoatl. Normally most people would overlook it or only care enough to grind for its soul, but it does have a meaning there if one considers what happens later in game. A Quetzocoatl is essentially a White Dragon controlled by a Fleaman. Dracula literally means "Son of the Dragon". Given that Soma is Dracula's reincarnation who absorbed a soul he couldn't use but was still within him (Dmitrii), the placement of the enemy is Foreshadowing of what Dmitrii is trying to do to Soma: hitch a ride on him to get control of his powers!
Soma's case of Bag of Spilling may seem silly, but Japan is a place with extremely stringent laws on weapon possession. A teenage boy lugging around numerous weapons would definitely get into hot water unless authorities (e.g. a government agent) confiscate them. And he just so happens to have a government agent as a trusted ally...
Why does Soma Freak Out in the bad ending? Well, he is a teenage boy who had to fight for his life against monsters twice within the span of a year or so, has the knowledge that he is essentially the universe's equivalent of the anti-God, and had just killed a man in self-defence, so his mental state would already not be the best. Seeing what appears to be his girlfriend getting killed is The Last Straw, and without the calming effect of Mina's Talisman, Soma promptly loses it.
If the player defeats Dario at the Castle Pinnacle without destroying the source of Dario's power, Arikado will arrive on the scene after the battle's over. Worth noting is that the room this takes place in houses a giant mirror at its center, and Arikado's reflection is not visible in it. Makes sense, given Arikado's true identity.
The description of the Rusty Food Tin. "Are you brave enough to open it?"
What happened to Dario and Dmitrii in Julius Mode? When you fight them, they don't even talk, which is really weird given that they were part of the reason why everyone was in the castle in the first place. No one tries to reason with them. In normal mode, at least Dario yells at Soma before fighting. What did Dracula do to them? What's more, Dmitrii is arguably dead at this point, and under Soma/Dracula's dominance. Is this what happens to humans whose souls Dracula steals and enslaves? Can't talk, can only do what Dracula says?
Julius Mode is kicked off by Soma being gullible enough to think that Mina died... right? Mina makes no appearance nor is mentioned in Julius Mode, and it's only said that the Mina that Celia shot dead was a fake in the good ending (which obviously never comes to pass in Julius Mode). What if, thanks to Schrödinger's Gun, Julius Mode started with the real Mina being killed?
In the bad ending, Dracula is successfully reincarnated. Who's to say that the Vicious Cycle of him returning every 100 years hasn't restarted?
In such a scenario, Julius would need to sire offspring to wield the Vampire Killer again, with Alucard picking up the slack.
Between Aria and Dawn, Soma releases every soul he had. If he took Galamoth's soul from the lantern in Aria (which might be canon because it's technically necessary for the true endings note Galamoth's soul is needed to get past the Chronomage, who guards a hint to equip a certain soul at the Graham Jones fight. It doesn't matter if you have the hint as long as you have the right soul combination, but in-universe, Soma wouldn't know otherwise), Soma released him. And since he didn't fight Galamoth in Dawn, he's probably still out there.
Soma and Mina undoubtedly had several classmates that they were well acquainted with. Assume that Schrödinger's Gun was in effect in Julius Mode. How is Arikado going to explain what happened to them? Worse still, how will he explain it to their parents?
