Ralsei appears as a short Darkner resembling a boss monster. He wears a wizard's outfit, complete with pastel-green tints on his clothes and hat. He also has a long magenta scarf wrapped around his neck and dons a pair of green colored glasses. When taking off his hat, it is revealed his face is quite similar to that of Asriel's Undertale counterpart. Ralsei is trusting and optimistic, often to a fault. Ralsei seems to always be grateful for any positive interaction with the people he cares for.