How about 3, 4,6, 7, 12, 13, 14, 17, 19, 20, 25,27,28, 29, and 30 foooor Sebagrelle ;3
Every few years, they'll have a dispute over getting a dog. Grelle would love a little white froo-froo dog to carry around in her purse; Sebastian will not allow a wretched cur in their house under any circumstances, thank you very much. D:< The demon and reaper also occasionally squabble over clothes if they both want to wear the same outfit or pair of heels on a particular day. And, of course, there's the decades-old argument over whether their meeting was mere coincidence (as Sebastian insists) or fate (as Grelle adamantly maintains).
4. Favorite non-sexual activity?
Dancing! In public, this appeals to their exhibitionist tendencies, since the graceful pair inevitably dominate the venue, whether it's a ballroom or a club. Grelle loves the romance and spectacle, while Sebastian views dancing as an opportunity to flaunt the fact that this incredible woman is his mate.
6. What is their favorite feature of their partner's?
(I'm assuming this means physical features?)
Grelle firmly maintains that Sebastian's eyes are his best feature. They're her favorite color, and burn with a hellfire that never grows dim. Her acceptance of his demonic nature made Sebastian fall even deeper in love with her when they were first courting. >w<
Sebastian utterly adores Miss Sutcliff's hair. Sensory demon cannot get enough of how lush and silky it is, and he'll often pamper Grelle by combing and styling her locks. He also considers her teeth extremely sexy, because they're a reflection of her wild, ferocious side. >:3
7. What's the first thing that changes when they realize they have feelings for the other?
Sebastian's instinct upon realizing (to his horror) that he's falling for Grelle is to deny, deny, deny. H-he has a crush on Sutcliff, of all people?! What insanity is this? The Phantomhive butler would never stoop to such things...even though Grelle is gorgeous and one of the most powerful reapers he's ever met and...oh, dammit...
Grelle is so accustomed to rejection that she tries not to put too much sincerity behind her flirtations; a lady's heart can only be trampled upon so many times. Therefore, when she realizes that her feelings for Sebastian go beyond a mere crush, she's caught off guard. Grelle's not stupid, and she's aware of how potentially dangerous demons are, not to mention the punishment she'd face for dallying with one in earnest. She needs to withdraw and do some serious soul-searching before deciding to see this relationship through. After all, the heart cannot be denied...
12. Who initiates kisses?
Sebastian! This may seem counterintuitive since Grelle is more impulsive, but initiating kisses is a tacit way for the demon to tell her "I want you, I choose you, I'm continuing to chase after you just as you chase after me." >w<
13. Who reaches for the other's hand first?
Grelle, by a slight margin. My headcanon is that Sebastian loves holding hands with his romantic partner(s), but Grelle tends to beat him to the punch; she's the type who will walk hand-in-hand or arm-in-arm with her s/o literally anywhere.
14. Who kisses the hardest?
Maybe Grelle? I feel like her legendary teef give her an advantage in this area. XD Sometimes she'll inadvertently (or accidentally-on-purpose) nick the demon's lips, but Sebastian doesn't mind. >:3
17. Who says I love you first?
Grelle. One night, she and Sebastian are sitting on the roof of the Phantomhive manor, hanging out after a playful sparring match. Grelle abruptly goes silent before quietly admitting that she loves him. "I'm afraid it's the genuine article, darling...though who's to say whether we're players in a comedy or a tragedy," she adds, glancing down.
The demon takes a moment to process this (sweet hell, she actually loves him!!!), but takes her hand and tenderly kisses it.
"Then let us see how it ends, rufina."
19. Who tells their family/friends about their relationship first?
Technically, Sebastian doesn't tell the other Phantomhive servants about his courtship with Grelle (and for obvious reasons, he daren't give the young master cause for suspicion), but it doesn't take long for Bard and Mey Rin to realize the dork is in love. Bard notices how dreamy and flustered the butler is these days, as well as the long red hairs that occasionally cling to his tailcoat (Miss Grelle has a tendency to shed). Mey Rin could've sworn she caught a trace of woman's perfume the last couple times she walked past Mr. Sebastian, yes she did! Mey is initially crestfallen but later gets together with Paula, so all's well that ends well, while Bard mercilessly teases Sebastian about his "new gal."
"I don't know what on earth you are talking about," the trash demon mutters. Sebastian also ends up discretely discussing the relationship with Agni. When he and Grelle have their first big fight, he asks the khansama for advice on how to make up with her.
20. What do their family/friends think of their relationship?
For a long time, Ronald is the only reaper aware of Grelle's relationship with Sebastian. Knox disapproves because he's worried that the butler is using his senpai to obtain information or gain her support as another of the Phantomhive brat's pawns. However, he later develops a grudging respect for Sebastian when he realizes that the demon truly loves her.
The servants never learn exactly who Sebastian's lady love is, but they're very supportive!
25. Who needs more assurance?
Grelle. She's grown accustomed to being misunderstood and pushed away, so she needs affirmation that Sebastian is loyal and won't ever desert her. Of course, in happy fanon land, Sebastian is unequivocally devoted to his wife.
27. Who would sing their child back to sleep?
Both of them! Their kids have fond memories of their parents harmonizing together when they needed to be soothed after a nightmare.
28. What do they do when they're away from each other?
In the canon timeline, Grelle is focused on reaping during business hours. In addition to her beauty appointments (hair and nails must be maintained at all cost!), she also enjoys going out to cafes or hitting the pub with Ronald, Eric, and other people from her small group of work friends. Sebastian's butler duties keep him busy, and he tries to distract himself by playing with his cat or reading in his small amount of leisure time (he still ends up pining for Miss Sutcliff, though).
29. One headcanon about this OTP that breaks your heart?
A constant terror that lurks in the back of Sebastian's mind is the fear that O!Ciel will learn of his relationship with Grelle and command the demon to harm or kill her.
30. One headcanon about this OTP that mends it?
I headcanon that Grelle is somewhat touch-starved, which is why she makes her little dollies to sleep with. After Sebastian finds out about this, he surprises her on their first Valentine's Day as a couple with a special Funtom rabbit in a red dress. When she has to go for long periods of time without seeing him (they have to exercise extreme caution when planning their trysts) Grelle will cuddle the bunny, which serves as a tangible reminder of Sebas's love for her.
