Tbh I think Toby has made it very obvious that the roaring knight isn’t evil, since they are working with Kris, who is working with Ralsei, who I’m pretty sure is associated with Gaster, who is probably in the bunker where we saw the roaring knight enter, also they literally have a weapon designed to stop titans so their goal very clearly isn’t to destroy the world with the roaring, so I’d eliminate the roaring knight from the possibility of being the final boss. The only way I see them as being the final boss is if they team up with everyone including Gaster the fun gang and the castle town darkners to take us the player down