When I wrote the app for Holmes I left out any possible imaginings for Holmes because, well, frankly none of it is canon and it would all be conjecture, and I wasn't 100% sure about any of the canon I may be inventing. Also, to be honest, I've always been rather shy and nervous about Holmes because he's such a well-known figure, and I'm new to the fandom, having read the stories this past December, finishing up in January. Jessie (armydoctor) is the one who got me interested in it, and in playing Holmes, through Watson and fanfic she linked me. I remember I decided to read the stories because I had just finished consuming all the fic I knew of at the time by this one author and I was like, man, I have to read these stories since I love the fanfic so much. Once I picked him up I was always (self-)conscious of how new I was compared to other people in the fandom, and so was hesitant about overstepping his characterization and what ACD gave me.
Some things I had firmly adopted as head canon -- you know, like, the thing where Holmes is gay and always has been, and the whole thing about how Victor Trevor (Holmes's only really close friend in university and the guy who helped lead to Holmes's his first case) was undoubtedly Holmes's boyfriend. I mean, come on, Holmes spent a month in Victor's house on vacation, okay (which isn't necessarily unusual for the time, but still). They were doing it. I also had adopted the notion that Holmes would have at least attempted to court a girl once -- just to see if he would be interested. (Hint: He wasn't.)
In light of Watson and Holmes's conversation about Robin Hood and Maid Marian and the impact these two had on their childhood, I started really letting myself think about Holmes's early life leading up to where we pick up, once Holmes has moved out. This resulted in me word vomiting a lot to Jessie, but as Jessie is sort of my Holmes/Victoriana spell check, able to add squiggly red lines where things don't sound right, I feel that even though I'm new to this, my conjecture isn't out of the realm of possibility.
I'm uncertain as to how much of this I may or may not fold into Holmes's history here, but I'm more or less happy with all of it, and wanted to document my little rough narrative of Holmes's life somewhere, and his journal seemed like a good spot. :|
Before I start rambling on about specific details of Holmes's life, let's start with something we know a little about: his sibling(s?).
We don't know if Holmes has any other siblings, and the fact that he never mentions them doesn't really count as definitive evidence because it takes him a forever to bring up the brother he does mention, and he also never once ever mentions his parents, and he has to have some of those. Mycroft is seven years older than him, which is quite a gap if he doesn't have any other siblings, though not enough evidence in my opinion to sway me to believe that he had some other brothers or sisters knocking around.
Actually, one thing that's making me wonder if he maybe had another one is something Jessie mentioned to me -- something that makes other people wonder -- and that's, well, who's inheriting the Holmes estate? It's clearly not Mycroft -- he's living in London -- and it's certainly not Holmes, who is in fact often strapped for cash (which suggests he has been disinherited).
If Mycroft is the oldest brother, the estate and everything would go to him, but if there were an older brother, then he would get everything and it would be his responsibility. I'm really not convinced enough yet to say there's another brother, but I'm rather open to the possibility. I'd need to hear someone make a case for it, but I can see Holmes being a surprise baby after his parents thought they'd had their set of boys. I'm not including the other brother here, but I'm not firmly opposed to his existence; I just don't have a reason to believe in him yet. (oh god is there a fairy dying somewhere, should we start clapping) ((wait am i saying the eldest is gay, i don't think he's gay)) (((well i'm not saying he can't be gay either... MOVING ON)))
My take on Holmes in his youngin' days is that he was an active nerd. You can't take a man who was a prizewinning boxer and a fencer and a martial artist and amazing with a riding crop and able to scale unscalable cliffs without dying and say that he mostly just sat around on his butt reading when he was a kid. I picture Holmes as crawling everywhere in the dirt, looking at bugs, looking at insects, learning dirt and grass and plants and birds and animals. He'd read about these things too, of course, carry books with him and chill outside, or inside when it rains.
He squeezed what playtime he could out of Mycroft before Mycroft got too old -- I really love the idea of Mycroft just being like, oh look, oh no, my leg is broken, I'll just sit here and read... play around me... -- and then once Mycroft was too old/Mycrofty to do that with him, that's when he started getting involved in all sorts of sport things.
Adolescence and Being Gay
As Holmes got older, too, and stopped playing more and more, he got increasingly interested in science and would do experiments with whatever he could get his hands on. He and Mycroft would, of course, play games of perception and deduction; it was a parlor trick, a hobby, a silly thing they did together.
Holmes found himself a friend in a similarly aged boy -- originally I had thought someone of a lower class, but I think someone around the same station as Holmes would be better because then they could hang out all the time and it wouldn't be a big deal. Which is especially helpful if you consider my FANTASY OF THEM RUNNING OFF AT NIGHT TO SLUM IT TOGETHER. So, if they live in the country, this possibly requires trips into London, and maybe prolonged stays in London (with family/guardians/etc., not just the two of them), which may be easier if they're the same station. I don't suppose it's entirely NOT possible for him to be lower than Holmes, though.
Okay, so like, Holmes knows a shitton about acting and also costumes and stage makeup, and also boxing. I fail to see how his parents would be like, HEY HOLMES HOW ABOUT A MAKEUP CLASS or, HEY HOLMES WANT TO MAYBE BREAK YOUR FACE AND BE A BOXER? So I figure Holmes learned about that on the sly, chillin' with his bff, hanging around at theater houses and trying to cover up whatever injuries he did get, lolz. He's an A+ violinist, too, so maybe he wound up playing in orchestras or whatnot, maybe that's why he would stay in the city for a while at a time, and that's also how he found out about makeup and costumes, and how he honed his acting skillz.
Somewhere in here, too, is the possibility of spending time in France since he's got that French grandmother. And France is a great place for a couple of budding gays interested in slumming it with theater peeps.
He also hones his acting skillz when he winds up courting a girl. He may be sorta pressured into it, he maybe just kind of went along with it, or maybe they've been fixed for a match for a while, but Holmes starts seeing this girl. He's okay with it; he can get along with women (he shows skills at knowing how to calm and pry information from them) but he's definitely not interested in her. At least, not nearly as interested as he is in his bff.
This is all pretty key to Holmes coming to terms with the fact that he's gay. Theater places are pretty notorious for being breeding grounds of alternate sexualities -- or at the least acceptance of such things -- and so Holmes is able to figure out both what gay is (and that he's not alone, and also maybe know a few other gays) right around the time that he and his bff start fooling around. This is Holmes's first blush of love, that teenagery kind where it's all excitement and foolishness.
Getting Caught and University
Somehow, someway, he and his bff are caught. Holmes's parents find out. Bff's parents maybe find out, but bff is clearly out of the picture. Holmes and the girl break up -- maybe his parents do it so that she won't find out, or maybe she finds out and has been suspicious all along, or maybe she finds out and breaks it off. Either way, she gets hushed up. His parents cover everything up, and only his family knows what happened; still, they're pretty much done with their son, and they disinherit him and never really speak to him again. They're not totally heartless; they send him to university, and Mycroft is informed to look out for him (or Mycroft takes it onto himself), but they pretty much don't have anything to do with their son anymore.
Mycroft, for his part, maybe is told about what happened; maybe it's kept a secret from him, maybe he figures out on his own. I can't picture Holmes flat out telling him. Mycroft finds out, somehow, and frankly doesn't give a crap. He loves his brother, annoyingly active as he may be, because he can understand him maybe better than their parents, and he knows that Holmes being gay doesn't really change much. Or maybe he's too lazy to give a shit. But whatever way, Mycroft is Holmes's only real family now, and he's pretty protective of him, so he doesn't talk about him much, and he's maybe a little shy around him, nervous, and especially nervous when someone else (i.e. Watson) is also there.
Before this, Holmes has been developing into himself. A little insecurity masked with pompousness, but he had been fairly social, hanging out with theaterpeople and boxing and whatnot. Losing his boyfriend the way he did absolutely devastates him, and his insecurity is ramped up, as well as his fear; he isn't ashamed of being gay, but he's just afraid of being found out because now he doesn't know what will happen. He's pretty depressed and antisocial at university.
Then he runs into Victor Trevor (and his dog) and they hit it off, and Holmes falls for someone again. Maybe not as hard as the first boyfriend, but it's a relationship and Holmes feels the damage that was done starting to repair itself. He's not as social as he was, still, but he's slowly returning to confidence, to being comfortable, etc.
During the Victor period, Holmes may have taken up some acting lessons at university, returning to the theater; maybe he played in the orchestra, or went on stage, or helped with makeup (because he's sure as hell awesome at it).
Then he and Victor are caught. Maybe by Victor's dad when Holmes is working on a case for them, maybe when Holmes is staying at Victor's house for a long period of time -- somewhere along the way he loses Victor around the same time he begins the greatest adventure of his life: being a consulting detective. It's Victor's dad who really gives Holmes his first case.
Losing Victor is really like the last straw for Holmes. His two major relationships have been snatched out from under him because of the illegality of their nature, and while Holmes knows there's nothing he can do about the way he is, he's pretty depressed and lonely, but too afraid to start branching out again.
Mycroft has been keeping Holmes afloat, and Holmes has been throwing himself passionately into his studies, as well as settling into the more or less antisocial guy he is in the stories. The time comes when Holmes needs to set himself up somewhere because Mycroft can't keep it up for forever. Maybe Holmes continues his time in the orchestra or the theater, to earn some cash.
Holmes finds a really, really awesome place to live, but can't afford it, and then along comes Watson. Holmes thinks he's definitely cute, definitely damaged from the War, and definitely dangerous, but he needs a roommate and a place to live and would rather live with a roommate he would like a little too much than one he would want to shoot a V.R. in.
AND THE REST IS HISTORY~*~
The Impact of This
When it comes to romantic relationships, Holmes is frankly terrified because all they ever seem to do is end tragically because of the nature of the whole gay thing. It's difficult for him to let himself commit; it was much easier to suffer for loving Watson from afar than it would be to be in a relationship with Watson because he feels more confident about hiding his feelings than he does about hiding a relationship. Or, at least, he can always blow up at Watson and be a jackass to him and put some distance between them.
Also, all of this pretty much ruins Holmes's enjoyment of the country, which is where he associates his boyhood/a fair amount of happiness, but it was all yanked away over something he can't control. This is why he shares some awfully negative opinions about the country in the stories, but then eventually winds up retiring to keep bees. (OR AT LEAST THIS IS ME ATTEMPTING TO EXPLAIN THIS WTFERY. WTF, ACD. WTF.) He really does enjoy the country -- and insects -- but it takes him a while to come to terms with what happened to him to be able to return to his roots, so to speak.
I wouldn't say definitively that anywhere in canon he and Watson shacked up. Maybe that second(third?) wife for Watson was woven in as a blind, maybe they raised some beeeeeeeeees together, maybe the two of them had a fling and moved on (or not), idk.
That was really tl;dr and I commend you for making it this far. I may add/edit to this as I get more ideas/change my mind, etc., and some of this may turn up in Holmes's tags down the road.