#(lore stuff)

They both consider their states to be some sort of void born illness they contracted aboard the Zariman (Gareth's being during the longer stay he had on the Zariman and Orthus' being on the return during angels of the Zariman). While Orthus' condition gets worse the longer he is in the void, Gareth's gets worse the longer he is away from it.

Even though they are both the same "soul" they consider each other to be more like siblings seeing as they more are mirrors of each other rather than the same person raised under different circumstances.

Another example of how different they are void wise is during transference Gareth appears more like a shiny star-like apparition in the mind of whoever/whatever he is in while Orthus looks more like a small ball of stars.

but on to the void angel stuff-

Gareth is more based around kaithes/kelpies so he is more about sheer size and force. His void angel is larger and can maneuver at high speeds (often on all fours).

He is more comfortable in this larger form as he often feels like he's "squished inside" his human body causing him pain and headaches from the force of keeping together

His personality doesn't shift much when he changes as he's still quite friendly and docile with an almost unnatural feeling of comfort around him and the song of the angels he carries with him is more like a lullaby than a droning hum

Orthus

Orthus is based around fairies and the fey in general. Unlike Gareth they are more calm and prone to deal making and trickery rather than kindness to get them to their goal. Much like themselves, their void angel is very agile and is good at hiding and flying.

The form feels unnatural to them as it was only recently it began to happen, and it terrifies them that they too can be incased in unfeeling metals. This change does aid them in a sense as it takes over for their bodily functions but it also brings the pain of forcing their broken body to work at full force.

When this shift happens it tends to be rather quick and violent for them and they often loose track of themselves until it is over. While they don't actively try to harm people their tricks and games tend to become more violent in nature though they can become agitated and aggressive if their games are ignored. Most times Orthus hides himself away when he feels the changes coming so he doesn't torment anyone (namely Loid who once had to endure a horrible game of "tag").

His song is also quiet deafening to endure and is more similar to a sirens call, often luring those unfortunate enough to be near him during this episodes into his little games.

Some other things about them if your interested-

Gareth looks different from Orthus because his body manifested to resemble one of their favorite characters from their childhood storybook.

Orthus does most of the fighting and strategizing while Gareth takes care of the weapons and frames. as well as generalized crafting and alchemy. He also sews floofs and clothing in his free time (that somehow randomly appear in peoples belongings).

Despite Gareth being the stronger more hands on sibling he is actually the less violent one; choosing to see light in people whereas Orthus operates on the idea the a dead problem is not a reoccurring one