Firstly, you still have to follow your high concept justification of your powers. Claws don't have to be Claws - a Red Court Vampire can take Claws to represent Fangs. But a RCV can't take Claws representing, I dunno, "Burning fists of fire", because powers have to follow high concept and setting logic.
I'm aware. But that's obviously not a problem here. A fetch changeling who shapeshifts is a pretty normal concept for this game.
For Modular Abilities specifically, even if we're no longer worried about high concept and are focusing on the power itself, its main effect is literally called Function Follows Form. It starts off with "You may shapeshift your form to take on a variety of abilities [...]" - to me that says pretty strongly that you pick your abilities based on the form you're in, not just willy-nilly.
You pick your abilities and your form and they should match. But there's nothing in the book that even implies that powerful forms have to be obviously inhuman.
And even if there was, it wouldn't affect this character significantly.
And even if it did, looking weird is mostly Compel fodder. It would focus the spotlight even more heavily on this character.
But I really don't think Dresden Files is very well suited to doing "strict by the wording" reading of powers without GM oversight making sure what you do mechanically fits in with the narrative. That's my advice to the original poster at least.
I'm not quite sure what you mean by this. "The game is badly written, so fudge it"? "This is a story-based game, so you should use a lot of discretion"?
Either way, I disagree. The writing's not perfect, but it still runs pretty well out of the box. Even stuff like your acrobat-sloth works out surprisingly well when you use Aspects. And other games with similar concepts, like Fate Accelerated, run very well with robotic rule-adherence.
Incite Fear should definitely be on the character sheet.
No it shouldn't. It's almost completely unconnected to the character concept. It'd be offensively out of place.
Sure, it's central to the parent. But Changelings don't always reflect their parents that closely. You pick and choose from their list of Powers, and you don't have to pick the iconic ones first. Which is good, because it means two very different Changelings can have similar parents.
...
The reason I'm being so argumentative about these points is that they connect to a very common and very bad response to situations like this one. Namely, handicapping powerful characters by declaring them narratively inappropriate.
Trying to fix a character's mechanics by attacking their story side is just not ever going to work.
Because even if the player listened, and changed their concept around, it wouldn't fix the problems. A character can be totally awesome narratively and also game-wreckingly powerful. And if you "punish" them with in-game blowback, you're just making the problem worse. Because then the events of the story are centred on this character, who gets to outshine everyone even more. Plus, the other PCs might not be able to handle punishments aimed at such a strong character.
With that in mind, that character there looks better story-wise than most of the PCs I've seen. The mechanical side's a bit sketchy, but the concept seems solid.
And anyway, the whole line of criticism is rude. The player sounds like a decent person, and they deserve better than that old "role-playing, not roll-playing" canard.
