The Throne Defender and Throne Watcher are a duo who reside within the Throne of Want coliseum. The Throne Defender appears to be male and has a very long white beard (not part of the helm) which indicates he has been there a very long time. The Throne Watcher appears to be female, though may be androgynous because of the item descriptions associated with the Throne Watcher calling it a “he”. This gender confusion appears to be a mistranslation on the part of the From Software team, as the items which give a specific gender in English, do not have any gender pronouns in the Japanese. The Throne Watcher also has a very feminine appearance and a women’s voice.
Whatever the case, the Throne Defender and Throne Watcher have souls steeped in Dark. This may be because Vendrick never sat upon the Throne of Want and linked the fire, therefore allowing the fire to go out and ushering in the Abyss. We know that proximity to the Abyss corrupts a soul, and this seems to fit the description of the Throne Defender and Throne Watcher.
The throne of the King is sacred and requires an appropriate guardian (the Throne Defender). This makes sense, as it would be foolish for someone to try to link the fire with a frail soul. The throne must also be observed closely at all times (the Throne Watcher). The two roles suggest that one looks outwards from the Throne (Defender) and one looks towards the Throne (Watcher), though they will both attack you upon entering their chamber.
The Defender and Watcher are both said to be waiting for something. From their roles and positions, it seems most likely that they are awaiting someone who is strong enough to take the Throne of Want, and they have stood beside this Throne for ages.
We do not know who the pair are or where they came from as they appear to pre-date Drangleic. There are some interesting things to note about them though. The Defender is capable of buffing his weapon with lightning, while the Watcher buffs with magic. The Defender wields a shield permeated with powerful magic and the Watcher wears armor with high magic defense. The Watcher’s shield was made of an old sacred chime and she is capable of casting Wrath of the Gods. These two certainly have some of the qualities of a cleric and therefore resemble Velstadt in certain ways. They are both able to be poisoned, and it would seem they are not golems or anything the like.
It may be that in ages past a king did burn himself upon the Throne of Want and linked the fire. These two may have been tasked with ensuring that the next heir to attempt such a feat was powerful enough. But no one came to challenge them and the Throne went cold under Vendrick’s neglect. Still, the pair awaited a new challenger, as their souls were slowly corrupted by the Abyss that seeped into the throne room.