I don't think the roaring knight is the real Dess but is actually something born from darkness that resemble/mimic Dess. Similar to Ralsei look like Asriel. And I think the real Dess was still lost in the code
I like the meta type of theory a lot.. like player interpretation of character directly affect how they are in the game even though it might be a bit farfetch.
or Maybe I just enjoy listening to some wild theory-
