HOMICIPHER

αℓρнαвєт - 𝑀𝑟. 𝑆𝑖𝑙𝑣𝑎𝑖𝑟

SFW
A = Affection (are they affectionate and how do they show it?)
I wouldn't necessarily call him "affectionate", but he has his moments. He won't hesitate to touch anyone, whether it be a comforting, reassuring touch or a more firm grip on the shoulder as he asks if he can research them. That said, once he's comfortable with you and has established you as one of his companions, he's surprisingly touchy. Gentle brushes of his hand or fingers against yours, tenderly gripping onto your arms from behind, bending down to your height to wrap his arms around you in a very gentle embrace, as he fears hurting you; and many more casual ways he can softly make his physical presence known. His most prominent way in showing affection, in some sort of twisted way, is asking to research you. It shows his interest in you, and his desire to intimately know your body—whether it be purely for science or for personal endeavors is unpredictable.

B = Best Friend (what does friendship with them look like? How would it start?)
Being friends with him is calm. It simply starts with a chat, and letting him care for you a little bit. Just allowing him to give you a room to stay in, some food, and company will be sufficient to begin a friendship. This is when his analysis of you will begin, in order to decide whether you are compatible with him as a friend/partner or not (Mr. Chopped didn't have to go through this, because he is merely a research specimen that Mr. Silvair just so happens to enjoy as company). During the time that he analyzes you, he cares for you in every way you'll allow—food, water, a "home" in his base, and just about anything else you ask for. He is the "mom" friend of the group, for certain.

C = Cuddles (do they like to cuddle and how do they cuddle if so?)
Oh my. He's actually the cutest boy for cuddling. He loves it! Similarly to Mr. Machete, when it's time for Mr. Silvair to settle down, there's nothing he loves more than to settle into bed with a book, with you cuddled up against him, one arm around you as he reads to you. Once he finishes a chapter or two, he turns off the light, and pulls you in close to him, nuzzling your face into his chest and holding you close, kissing your head and whispering sweet things to you in his language—things he knows you don't understand yet, but he plans to teach you. 🥹 He especially likes it when you're cuddling like this and you put your leg between his, or wrap your leg around his hip, as if you're entangling into one another. He loves that just about more than his research (which is a huge deal).

D = Domestic (are they settling down? Do they cook and clean?)
Mans is already locked down at his base, taking care of Mr. Chopped. He'd be more than happy to welcome another helping hand into his group—especially one he can... research... with your permission, of course! He bought cooks and cleans; after all, taking care of Mr. Chopped is no easy job. He cooks meat, and sometimes, he even finds other little treats to cook for you, as his "partner in research"... which for his kind of research, it's basically the same thing as crime.

E =Ending (how would they end a relationship if they had to?)
If he had to end things, it would be very straight forward and to the point. "αяяαиgємєит иσ ωσяк. уσυ мє иσ иєє∂ ѕєє мαиу мυ¢н мσяє." However, this would happen early on. He would study your behaviors and your character with agonizing scrutiny to determine your compatibility with him, and even on the slightest indication that you are not fit to be his companion, he would cut things off (romantically, at least). Once you've hit a certain period of time without him saying this, it's safe to assume that he's deemed you a compatible partner, and you should have no worries of him randomly popping out with a somewhat humbling statement such as that.

F = Fiance (how committed are they? How quickly would they want to get married?)
As I just mentioned, he takes his time researching you, but once he's certain you are a valuable companion, his commitment is unwavering. The only creature who he would genuinely struggle to choose you over is Mr. Chopped, his first true friend and willing test subject. There would definitely be a few times where he said no to doing something with you in order to do something he found more appealing with Mr. Chopped—but he cares for you no less just because of his habitual endeavors with Mr. Chopped.
If you asked Mr. Silvair for a wedding, he would agree, but it would be small. Perhaps just you, him, and Mr. Chopped (Mr. Crawling would not attend—he would be devastated). But it would be just as you planned it—the formal suit for him and the wedding dress for you (all provided by the Bride, of course), the rings, and the most official wedding vows he can conjure up. But all this would happen at your request, and he would consider you both a "married" couple the moment he deemed you compatible to him and you stay around, living with him in his room.