So I've been rather active in an Undertale Discord group (thanks to previous Gaster project that introduced me to many amazing other artists!) and a random channel 'challenge' was to draw our Gasters in fancy wears. Well, with my Gaster, Vedvulon, already being pretty fancy as he is, the only step up from that was just Prince Vedvulon.

With his creation into existence being by Sildinok, the Toriel of his world, she would in such a sense be his mother and thus in their mortal lives with Toriel being Queen, thus makes Gaster an 'adoptive son' which gives him prince status. A status he doesn't really dedicate himself to and often times disowns such a title.
So such a fancier outfit for him would only reach into this factor for him, so enjoy a Discord-inspired 'challenge' of a suited up Gaster. :D