Designs:

Seb's design for Sabotage (By Aziarath ), An Impostor Among Us (By Ladyspiderbug ) and most Non-Canon appearances (With a facial reference)
(Artstyle inspired by Aesthethic_Cherry 's)

Official design of Parabottom/Joke PC

Reference Sheets:

Jokeware's reference sheet

Reference sheet of Soulmate.HX (GF-Based Character)

Miscellaneous:

Soul Girlfriend during a rare sane moment

Seb surrounded by Inventory Pets