(The Szoreny ideas here later served as the inspiration for my Szoreny Charmset, found at this link
Szoreny (EarthScorpion Charmset) )
So, let's talk Szoreny. What do we know about him at a basic level that can be used to consider what might exist in a Szorenyc Charmset?
- Szoreny is quicksilver, which is to say mercury.
- Szoreny is an inverted tree whose branches are buried and whose roots stick into the air. This is not his natural state of being, but was inflicted on him by the Exalted host.
- Szoreny is a mirror, who reflects countless warped versions of any scene - worlds to themselves within him. This is part of his fetich soul's themes, too - Kagami, the City of Mirrors
- Szoreny is envious. He focuses on people, becomes them, and so replaces them.
- Szoreny is enviable. Cecelyne turned her sands silver to be like him.
Now, Infernal Charmsets are kind of made so someone who focuses on just one becomes a certain kind of archetypical villain. And so - following some discussion with
@Aleph - I might suggest that the archetype that Szoreny should support is the type displayed by Gildroy Lockhart. Szoreny is a fake. A fraud. An envious, poisonous false-friend who takes your achievements and your reputation for himself. He obsesses over people who beat him and twists himself until he becomes them in every way and then replaces them. He's not the Ebon Dragon - no, Szoreny adores being the centre of attention. He's terrible at conventional stealth because he wants everyone looking at him, but he's a master of social stealth. And because he loves being the centre of attention, he draws strength from people envying him - even as he envies his foes.
Mercury is poisonous and slowly wasting, causing neurological disorders. I would combine mercury's poisonous nature with his envy, thematically and mechanically. Moreover, mercury accumulates and biomagnifies. That suggests that Szoreny wants to build envy in others over many scenes to slowly, steadily fill them with his mercurial envy - and so they become like him. Indeed, if we take the biomagnification and consider where we can go with that, that suggests that people who kill people who envy Szoreny start to envy Szoreny too, because the mercury builds up in them. Szoreny would therefore want, militarily, to build up an adoring cult-army who envy and love him so foes who slaughter his men like cattle envy and adore him too, the mercury in the blood they shed flowing into their blood.
Mercury readily dissolves gold and silver to form amalgams. This might potentially allow Szoreny to dissolve "gold and silver" - that is to say, Solars and Lunars, which is to say, powerful opponents - to strengthen himself.
Mirrors only reflect what they are shown. That suggests that Szoreny has little control over who he disguises himself as - unlike other disguise charms. He might only be able to disguise himself as people he sees, or as people he envies.
Naturally, a vital part of being a Gildroy Lockhart is stealing credit for other people's actions. That suggests that Szoreny should be able to bold-facedly say "Yes, I was the one who saved Creation from the fae by activating the Realm Defence Grid - but I generously let the Scarlet Empress take credit for how I saved the world" and have people believe it. Likewise, he should be able to hit people with an Illusion - including himself - so a person forgets the heroic deeds they did and everyone, him included, thinks he did it. This might extend as far as a Szoreny Infernal being able to murder the Bull of the North, activate a Charm, and now everyone in Creation remembers it as him being the one who beat the Tepets (this would of course require you to actually murder the Bull of the North).
Mercury is formless and protean. It is liquid and it flows, and conducts heat poorly even though it conducts electricity well. These are all useful properties for aesthetics - for example, his perfect might involve him taking the blow, splattering, and just reforming as per the T1000. Likewise, because he's protean he might not see very much difference between physical accomplishments and mental ones - what matters is
winning.
Mercury is a poison, but mercury is also very important in alchemy. Mercury use was thought to prolong life, heal fractures, and maintain generally good health, although it is now known that exposure to mercury vapor leads to serious adverse health effects. This means that Szoreny should be able to buff and enhance people who "consume mercury" - ie, who envy him - but at the cost of doing long term damage to them. This might involve converting their Attributes or Abilities back into XP to pay for the enhancements he gives them - which of course makes him even better than them and means they envy him more. This is a feature, not a bug to his mindset.
Alchemists thought of mercury as the First Matter from which all metals were formed. They believed that different metals could be produced by varying the quality and quantity of sulfur contained within the mercury. This also indicates that Szoreny should have "alchemy" as a significant feature of his charmset (so he can transmute his own flesh into many different things) - and do you know what that leads to? That leads to drugs. Specifically, that leads to performance-enhancing steroids rather than recreational drugs, which goes very nicely with his envy themes. He wants to be the best. He wants to be the very best,
like no one ever was and so "I take drugs so I can beat other people" is very much within his themespace. This suggests that his combat effects should be "combat stims" and performance-enhancing drugs - things that you activate to give you short-term bonuses, but if you keep the Charm active too long then you'll take long term damage. That means that quite a few of his buffs should have activation costs measured on a per-action basis, rather than being a flat cost for their duration.
I mean, that idea sounds amazing, but nitpick gonna nitpick. 
