Oh man, for the sibling meme, gotta be the Daye sisters (for an AU in which they grew up together as children... or not. None of faerie is above tattling to the folks well past adulthood.)
which sibling is most likely to cheat when doing chores
May. As she told Toby once, her magic isn’t “on the super-saver plan.” Toby’s more powerful than that now, but May is still a pureblood and therefore has more magic to expend getting the vacuum to go all Sorcerer’s Apprentice on the living room.
which sibling sleeps through their alarm until it wakes up the rest of the house
May again, since I imagine Toby is accustomed to situations where not waking up at a loud noise could mean she winds up wearing too much of her own blood.
which sibling is the best at making up cover stories when there’s Trouble
Toby. All those times she’s had to get the police off her case? All her experience with courtly manners? May may have her memories up to a point, but she also has a much more flamboyant personality. I feel like most of her cover stories involve unicorns. Evil unicorns.
which sibling threatens to rat the other(s) out to the parentals figures
August. (Gotta love a loophole.)
which sibling compromises about what to watch on netflix
Toby. I think May shares her taste in movies with most of the Lean Mean Sidhe Teen Machine(TM), so Toby gets overruled 90% of the time when there’s a dispute.
which sibling always responds last to text messages from the fam
Toby, usually because she’s comatose and/or fighting for her life.
which sibling keeps forgetting their keys/wallet/coat/homework/etc
Neither Toby nor May are particularly forgetful- you might think May, but her silliness hides an ancient cannibalistic psychopomp who will Take No Shit while wearing a pound of eye-searing costume jewelry -so I’m going to go with August again. She indisputably forgot the most out of the three of them...
which sibling invents elaborate make-believe games and forces the other(s) to play along
Listen, anything whimsical and young-at-heart is May. I imagine Toby was more down-to-earth even as a kid, partially because her mom abruptly withdrew from her emotionally and partially because that’s just how she is by nature.
which sibling always tries to cheer the other(s) up if they’re sad
...damnit between this question and the last, I’m having emotions about babby!May trying to mitigate the damage Amandine’s emotional distance had on babby!Toby. Although I think as adults they both try to cheer each other up in their own ways. May’s method seems to involve more reassurance and Toby’s seems to be more “let’s find a solution,” though of course there are acceptions to that rule.
which sibling would rather be alone in their room instead of socializing with people
Toby. Because that means she might- might -finally get a decent day’s sleep.
which sibling is most likely to finish the snack food/leftovers before anybody else can have some
The aforementioned Lean Mean Sidhe Teen Machine(TM) is not a sibling, but you know it’s the most accurate answer to this question in the Daye-Sollys (Ames-Lorden-Brown-Raj doesn’t have a surname) household. Nobody gets any snacks. All snacks are offerings to the horde of fae adolescents who periodically swarm the house. It’s like calling the night haunts, except easier and you get Teaching Moments instead of macabre information about someone’s death, and Toby only has to bleed sometimes.