DO ME A LUCIFER AND SARIEL BECAUSE REASONS *mhhg' sanderling chirpy noises*
I'm running this as human AU because 'shops for groceries' implies so many things about various national economic models
send me a ship and I’ll tell you who:
shops for groceries It depends. S shops for groceries, usually; L doesn't do so well in supermarkets. Colors + huge and echoey + people + SO MANY THINGS, WHAT DO, LOOK THAT'S SHINY = things not getting done and bad times for L. Or they go together, because L likes colors and objects as long as sy doesn't have to do things with them, and sy likes being with if there's a specific thing sy wants.
kills the spiders Nobody kills the spiders. L names the spiders. S sometimes absentmindedly squishes a spider and then L is mad at sym for the rest of the day. Both of them mostly ignore the spiders unless one is in the way, at which point L gently removes them with cup & paper and coaxing. Eventually they start walking into cobwebs and it becomes a problem (for L especially; spiders are friends, cobwebs are ghghghgehegfkhl;) at which point L reluctantly initiates a cleanout
comes home drunk at 3am Neither of them drinks. So nobody. In terms of disruptions at unreasonable hours, though, L is most likely to wake up at 3am really needing to write that down (whether or not it makes sense in the morning is a massively entertaining game of roulette)
makes breakfast They both make their own breakfast. This is because L can at least handle cereal, milk, toast, and yogurt. Once things like bacon, eggs, and pancakes start getting involved it quickly becomes S's job. L is an engineer, not a chemist, and fire alarms are terrible instruments of pain.
remembers to feed the fish snakes (fish are nice but snakes are cuddly) Either one of them. One would expect S to be better at remembering -- and L to be more squeamish -- but L has a surprisingly pragmatic view of predation for someone who names household spiders (It's different, quoth sy), and kind of likes watching the snakes eat. S is better at remembering, but is also more squeamish.
decorates the apartment Well, if by "decorates" you mean "collects various objects which were interesting or relevant at the time but may or may not continue to have any actual value, sentimental or otherwise", L. If by "decorates" you mean "arranges those objects into some semblance of order and collects objects that make more sense in a house", S. They've reached an agreement to keep (most of) the clutter to one corner of the main room that serves as L's workspace.
initiates duets L. Almost always. Because L is a huge dork.
falls asleep first Either. S goes to sleep at a fairly consistent time; L is all over the map. Sy tends to stay up late for several nights running, then crash hard. It's not the healthiest of habits, and sy's working on it, with some degree of success.