One of the newer additions into the Kingdom Hearts Universe would be the Lingering Sentiments. Now, as of now, there are only Two Sentiments that have been identified completly. Vanitas's Sentiment, and Lingering Sentiment (Terra's). There is also the possibility of Aqua's Armor/Keyblade in the Room of Repose being her Sentiment.
With the three sentiments above, there is one similarity that they all have in common. They all are created with the person's armour, and not the body itself. Vanitas's Sentiment is a black and white version of Vanitas, with the Unversed symbol on his helmet (Mainly due to the fact that he is the creator of the Unversed). Terra's is simply his armour formed together after MX took over Terra's body. Aqua's Sentiment, if it is hers, is her scattered armour pieces in the ROR.
While the armour may not have any such significance to how Sentiments are created/formed/born etc., one of the things that Sentiments do have in common is the fact that all of their 'originals' are no longer in the Realm of Light.
Aqua - in RoD with Ansem the Wise.
Terra - Inside of MX/Xemnas/Ansem (Whichever one now).
Vanitas - Dissepeared from existence pretty much, or inside Ven. One of the two.
Another large similarity connecting the three is that their originals all had the ability to wield a Keyblade. This leads to my theory, which is...
If a Keyblade Wielder, no matter whether they are on the sides of Light or Darkness, fall from the Realm of Light, they can create a Sentiment to take their place.
The theory makes sense, as it does encompass all three sentiments we know now. Vanitas, Terra, and Aqua were all Keyblade Weilders who fell from the RoL, and managed to somehow create sentiments on what was left of them. Terra's Armour, Aqua's Armour/Keyblade. Vanitas however, simply had memories of him left in the Realm of Light, which allowed his armour to be formed once again, but nothing else, as almost everyone never saw his true face. The Unversed symbol and black/white colours represent his connection to the Unversed and Ventus (Darkness/Light.)
This also explains why Ventus didn't create a Sentiment, or hasn't to what we know. Castle Oblivion lies in the midst of Light and Darkness, a Twilight Area. Technically, being in the CoA, Ventus has not fallen completely from the RoL, which could result in the fact that he did not form a sentiment, or he has partially formed one, but not to the extent that it has a main plot for the story.
Sora could possibly have two Sentiments, due to the fact of Ventus's, his, and Kairi's heart being released in Hollow Bastion. Technically, both Roxas and Namine are 'Special Nobodies', as they have both showed emotions. Now, Sentiments have been shown to have emotions as well, and have not shown to have hearts. This could mean that Roxas and Namine*** could be the sentiments of Sora, and Xemnas simply labeled them as 'Special Nobodies' due to his lack of knowledge of Sentiments.
Of course, there could be other Sentiments out there, including Master Eraqus's. However, this is just what I have thrown together.
Now, to recap, my Theory on Sentiments are that they are What A Keyblade Wielder who has fallen from the RoL has left behind in that realm.
With the three sentiments above, there is one similarity that they all have in common. They all are created with the person's armour, and not the body itself. Vanitas's Sentiment is a black and white version of Vanitas, with the Unversed symbol on his helmet (Mainly due to the fact that he is the creator of the Unversed). Terra's is simply his armour formed together after MX took over Terra's body. Aqua's Sentiment, if it is hers, is her scattered armour pieces in the ROR.
While the armour may not have any such significance to how Sentiments are created/formed/born etc., one of the things that Sentiments do have in common is the fact that all of their 'originals' are no longer in the Realm of Light.
Aqua - in RoD with Ansem the Wise.
Terra - Inside of MX/Xemnas/Ansem (Whichever one now).
Vanitas - Dissepeared from existence pretty much, or inside Ven. One of the two.
Another large similarity connecting the three is that their originals all had the ability to wield a Keyblade. This leads to my theory, which is...
If a Keyblade Wielder, no matter whether they are on the sides of Light or Darkness, fall from the Realm of Light, they can create a Sentiment to take their place.
The theory makes sense, as it does encompass all three sentiments we know now. Vanitas, Terra, and Aqua were all Keyblade Weilders who fell from the RoL, and managed to somehow create sentiments on what was left of them. Terra's Armour, Aqua's Armour/Keyblade. Vanitas however, simply had memories of him left in the Realm of Light, which allowed his armour to be formed once again, but nothing else, as almost everyone never saw his true face. The Unversed symbol and black/white colours represent his connection to the Unversed and Ventus (Darkness/Light.)
This also explains why Ventus didn't create a Sentiment, or hasn't to what we know. Castle Oblivion lies in the midst of Light and Darkness, a Twilight Area. Technically, being in the CoA, Ventus has not fallen completely from the RoL, which could result in the fact that he did not form a sentiment, or he has partially formed one, but not to the extent that it has a main plot for the story.
Sora could possibly have two Sentiments, due to the fact of Ventus's, his, and Kairi's heart being released in Hollow Bastion. Technically, both Roxas and Namine are 'Special Nobodies', as they have both showed emotions. Now, Sentiments have been shown to have emotions as well, and have not shown to have hearts. This could mean that Roxas and Namine*** could be the sentiments of Sora, and Xemnas simply labeled them as 'Special Nobodies' due to his lack of knowledge of Sentiments.
Of course, there could be other Sentiments out there, including Master Eraqus's. However, this is just what I have thrown together.
Now, to recap, my Theory on Sentiments are that they are What A Keyblade Wielder who has fallen from the RoL has left behind in that realm.
