Fi has two forms, because it is an ethical process and a rational process. All rational processes work via dividing/contrasting. This is the essential element of judgment: to discriminate/differentiate. Because of this, as explained in this thread, Fe has a polarity to it in how it manifests externally. Fi also has two sides in which something can land according to its ethical frame. However, Fi is not a proactive process so this contrast won't be visibly exerted, instead it will be internalized.
Unless the worldview function (Ni/Si) has deeply cemented some truth such as "all humans are evil by nature", Fi will still be capable of making decisions on both sides of the contrast: to consider some things/people/actions noble and others not so much. However, if the worldview process has at least ingrained something moderately close to that such as "most humans are selfish, and incapable of true love" then the sort of ethical calls it will make will continually lean toward the darker contrast. A perpetual state of this can cause a perpetual sorrow on the face. This is because Fi accidentally radiates an emotional aura according to how it judges things internally.
What I've called an "innocent" Fi in prior posts is the willingness of Fi to be unguarded. It is typically Te which is expressed as a safeguard for Fi. Because Fi itself is not a proactive process, yet it is an ethical judgment process, it will implement its ethical judgment via Te. Thus an Fi that is either afraid of the world or jaded against it will come off as almost entirely Te. But if this type is a high-Fi user, then the Te will not be able to fully conceal the "pained" sorrow that will also lie behind the hard shell of Te.
As I've posted elsewhere, an example of an unguarded/innocent/seelie Fi would be this young Evanna Lynch. Her footage starts at about 2:00.
FiNe Evanna Lynch Video Here
Notice at 2:11 how she shrivels back into herself, in a very giddy and bashful way. This is how Fi looks when it trusts the environment and people. Because Fi is a compass process (Ji) it does not lie to the user. It's stances are essentially their identity - just as I cannot fool my Ti when it sees a contradiction, even though the most I can do is ignore it for a while. This authenticity makes it so Fi cannot lie to itself about how it feels about an ethical stance/position. But unlike Ti, the stance Fi takes on a position also affects the user emotionally and in their countenance. A sullen/pained countenance is the result if it's judgments are chronically on the negative side of the judgment-divide.
An example of "unseelie" Fi, apart from Viggo, would be Kanye West:
FiSe Kanye West Video Here
This sullen/pained effect (unseelie) is more common when the user also has Ni/Se. And this is because the Ni/Se worldview is more stable, connected, and it is easier to maintain a perpetual opinion. Inversely, the levity and optimism that accompanies Ne alleviates this tendency to become sullen as Ne may open more positive possibilities/scenarios about other people, where Ni/Se wouldn't as easily. However, it really depends on the Fi's values, as an Fi may hold a value to be charitable regardless of the nature of those around it, etc.
- Fi Function Profile http://cognitivetype.com/profiles/fi.html