#nightshark

God I could rot about them forever. Ellery helped me drag some of our headcanons back up so I could answer this.

Ruin is super touchy feely and Moon initially is not and finds touch from most people uncomfortable (Sun and Lunar being exceptions) but he eventually finds that touch can be really comforting, so he'll spend the day curled up around Ruin, purring while he dozes.

Moon isn't a big fan of food but he enjoys baking for Ruin, because his rays always do a cute lil spin when he eats something he likes and Moon adores it

They also totally dance alone in the kitchen at 3 am when neither of them can sleep

Ruin sings a lot, has a really good voice for like broadway and stuff, which Moon enjoys a lot. But Ruin is always so ecstatic whenever he catches Moon singing to himself, he has such a soft voice for lullabies and getting children to sleep. But he's super shy and will only sing for the kids, he stops if any adults are around

However, Moon will hum lullabies for Ruin when he's having a migraine. (Ruin gets migraines from his sun and moon splitting every now and then. They're still a part of him and sometimes they try to peek out for one reason or another, although they're mostly dormant. It gives him really bad migraines.)

Moon likes to mess with Ruin's rays. It's kind of a stim for him that he'll do without thinking about it. Ruin doesn't mind

Ruin still uses his old battery pack even though he's in an upgraded body, so sometimes his battery will stutter out or get drained really easily, causing him to faint. The first time this happened Moon panicked and thought he just died on the spot and had the computer run diagnostics. Because Ruin had to be plugged in for the diagnostics tho he woke up (which also startled Moon)

I've always liked to headcanon Moon with lowgrade depressive schizoaffective disorder, which is a psychotic disorder, since he's admitted to experiencing long term psychosis, but he's clearly self aware about it and the symptoms are so severe that they keep him from functioning. After him and Ruin became friends, Ruin started helping him manage it so he wasn't alone with it. Even though Ruin doesn't have experience with the disorder, it reminds him of how his friends would act and how he would help them when the virus in his dimension started taking root.

Both Ruin and Moon struggle with making connections to others (especially Ruin who has ASPD), and they're both under the aro/ace umbrella, so even in aus where they are dating, they see each other more like close friends (with potential benefits) rather than lovers. Although they may use the term to distinguish their relationship from other relationships in their lives, even if they don't necessarily feel/have limited romantic attraction for each other.

Ruin deals with phantom pain (partially from his rusted battery which scrambles his internal sensors a bit bc it's not supposed to be there, but mostly psychological), and Moon helps him with it. Moon made him a cane for really bad days when Ruin's processors just won't do what they need to and he has trouble with balance and orientation.

When Moon was rebuilt Monty accidentally fucked up his optics, and so he had to wear glasses for a long time until he was able to get them fixed. After he got them fixed he just popped out the lenses and kept wearing them (partially because Ruin commented that they made him look more like *his* Moon, rather than Nexus or any other Moon out there. - "his" being possessive and not literally Ruin's moon that is part of him)

Ruin is constantly stealing Moon's clothes. They're way too big on him, but he will literally wear Moon's turtlenecks like a sweater dress. He doesn't give a fuck.