Doppelganger quickly changed into Dante and threw a ball of dark energy at the flare in mid-flight, completely swallowing it in a blast before it could fully light. The demon suddenly turned into Hermione just as Harry and Ron ran to it to attack, showing everyone that that copy was complete, and pulled a wand out of its wrist before pointing it at Harry. "Crucio." It quickly moved the curse on to Ron, Ankh, Teridax, and finally kept it still on Marvelous, all as punishment for wasted effort. "Oh, how I've always wanted to use this but never could...until now. Wouldn't you think a demon would know about such curses, if any of you are asking? In Hell, news about this stuff spreads fast." The darkness covering the ground receded back into Doppelganger. It soon stopped the curse and plunged the wand back into its wrist. "I've already claimed my prize. Perhaps not a soul, but a good enough replacement anyway. What about all of you? Have you acquired your prize yet? Or are you letting others down by being here instead of over there where you should be?" Doppelganger melted away in an instant and moved on elsewhere.
Doppelganger's appearance shattered in the light, leaving it as a naked Lexaeus. It covered its eyes from the brightness, howling and writhing in pain, stunning it and leaving it open for attack. Thankfully, Vexen giving it a body of liquid darkness made it much more resilient to light. After only a couple seconds, Doppelganger recovered. The demon jumped high into the air, barely evading the Getsuga Tenshou but not from Decade's slash, and slammed its fist into the ground, creating a massive geyser of darkness to erupt underneath itself and everyone near it. The geyser allowed it to reform its defenses and snuff out the launched flare, returning the battlefield back into darkness. "Well done. Now let's see if you can do that indefinitely." Changing into Fang, it cast a Hell Ruin at everyone starting with Marvelous. It was essentially a slightly stronger form of the normal Ruin spell, but blood red and can poison, silence, stop, and, in extremely rare cases, instantly kill the target.
The Zangetsu's swing severed its connection to Hermione's soul, but didn't actually do anything to the demon. It jumped back and laughed as it morphed into Xigbar, plunging its two arrowguns into spacial rifts. "Heads up." Multiple rifts circled the group protecting Hermione and fired out of random ones in short bursts. Then Doppelganger teleported in the middle of the group, changed into Lexaeus, and concentrated its energy into itself before releasing it in a massive, yet harmless blast wave to raise its power level to 10,100 and send everyone flying. The dark purple, smoke-like aura that covered the demon grew in intensity and size in proportion to its power level. "Come and get me." Like in its battle with Fang earlier, darkness seeped from the demon and covered the battlefield to create one gigantic shadow.
Fittingly rename every numbered Final Fantasy game as they were separate titles.
"Yes I know who you are, I was speaking to my prey." The syringe that was shot at the demon passed through it harmlessly or releasing any of its fluid. Doppelganger changed its form into Xemnas, turning the Keyblade into an ethereal blade, and boxed itself and Hermione in with dark red barriers that shocked anything on the opposing end on contact. It tightened its grip on her. "There. Now the interruptions will be reduced to a minimum. Hope you're a screamer, because I'd love to hear you struggle." The ethereal blade retracted back into its left hand, charging dark blue electricity into it. Then it shot that electricity into Hermione's chest to slowly rip out her soul.
"...you came..." Doppelganger grabbed Hermione's wrist before she could take off its hood and threw her to the ground before re-positioning itself on top of her. Its blood red eyes peeked out of the gap and looked into her's. Its voice once again returned to being a distorted impression of the person it mimicked. "Thank you for coming." It summoned a black Kingdom Key in its left hand and pointed it at Michal while gripping its right hand tightly over Hermione's mouth. "Attack and I'll take much more than just her skills and shape. Oh, but since we're both in such a hurry, you're gonna lose your identity either way, aren't you? Poor you...what was your name? I never caught it." Doppelganger chucked, and since it was in a distorted Xion, very disturbingly. The demon lightened its grip just enough so its prey could speak.
As the two broke off, Doppelganger left Hermione's shadow and swam on ahead to the center of the horde. Hidden in the chaos, it rose out of the shadows and laid on the ground as Xion with her hood up. All it could do now is wait.
With everyone on the run trying to catch up to Jecht, Doppelganger took this as an opportunity to separate Hermione (and probably Michal also since it noticed the two never go anywhere together) from the main group. So it set up an on-the-spot, simple lure. "Wait! Don't leave me here with..." Exerting its demonic influence over the Heartless, Doppelganger diverted their sole attention to a point where Xion's voice would logically be coming from to fake an attack. "No! There are too many! Please help me!"
A voice spoke out to Hermione sounding oddly like Xion from a far off distance. "Are you leaving me again?" Doppelganger made sure that she was the only one to hear it. Let the paranoia settle in for a bit.
Exaggeration for effect. A regular dodecahedron has twelve faces, twenty vertices, and thirty edges. I assume an involved character represents a vertex since that's how love triangles and its variations work.
A love dodecahedron would involve a good majority or at least a sizable chunk of the cast, maybe even a Dalek or two as a crack pairing. I pray this doesn't evolve into one.
Droid: Geomancer Machina: Alchemist DT: Summoner Me: Mime
As Hermione and Michal moved off, Doppelganger took this chance to close in on the lone pair. Figuring that Fang probably told them about it, the demon merged itself with Hermione's shadow and began memorizing everything about her that was practical to it: skills/abilities, appearance, voice, weapons, etc. It was too soon to approach them directly, anyway.
Four Black Mages, fists and Tier 1 spells only.
Vexen cleared his throat. "Well, I'm certainly never doing that again. Anyway, now that we're all here, I'll be going." He opened a Corridor of Darkness and turned to leave. ----- Somewhere not too close and not too far from Serah and everyone, Doppelganger was watching them. Although battle was the easiest way to learn an opponent's skills, soul devouring and shadow stalking were other viable methods, although the former would kill the host or at least reduce them to a living shadow like itself so that would be a last resort-type of option. As the demon continued to select its next target, it noticed people there seemed to trust Fang. Perhaps some manipulation of that trust was in order.
That should be fine. He could pretty much put up with anything after working for Liquid twice.
On the run from The Sorrow, yes.
Unsure where to exactly place Psycho Mantis. Is there any villain group that would be interested in having him?
To finish it up, Doppelganger teleported directly above Fang and plunged each arrowgun downwards into a rift. Countless spatial disturbances formed and rippled overhead. "Master? I think you're mistaken." Holding down both triggers, dark red laser arrows rained down from the overhead rifts in another barrage. "I work for no one." Once finished, Doppelganger was back on the ground. The darkness covering the ground receded back into the demon. Then surprisingly, the demon then changed its form into Fang's and spoke in its impression of her. "Now who's the one feeling the pain? But I gotta hand it to you, though: Never thought I'd ever get a chance to get you as part of my own, seeing as you weren't fighting in that tournament and all. But look at how things turned out..." Doppelganger's red eyes turned to Vanitas, looking rather intently at him. Or displeased. It was hard to tell. "At least I got half of what I wanted here. Warn the others if you so wish. They'll be next for my taking." The demon melted away back into the shadows, somewhat satisfied with what it got out of the fight. Now finished with Fang, it went off to find other prey.
"You look tired after that." Doppelganger teleported behind Fang as Xigbar. "Why not take a nap?" It began shooting fully-automatic in a complete circle before teleporting all around them to continue shooting at them from different directions. It seems the demon was testing how much they could handle by beating them down with each Organization member's ultimate attack in succession.