Well, firstly, I've always sort of had a different view of Orion as I do of Walburga, though in essence, he was a Black.
Going by the Black Family Tree (I swear, someone needs to ban me from examining that tree; I spend too many hours messing with it :p ), it's clear that Orion would have been the Heir of the Black family, though, because his father, Arcturus, outlived him -- Orion died in 1979, Arcturus died in 1991 -- he was actually never the Head of the Family.
Had everything worked out in different ways, Orion would have taken over as Head from his father, Arcturus, with Sirius, as Orion's first-born, being the next in line.
But, I digress.
Also, he would have been a contemporary of Voldemort while at Hogwarts, though a couple years younger. The Lexicon has Voldemort going to Hogwarts from 1938-1945, and going by Orion's birth year of 1929, we can place him as attending Hogwarts from around 1940-1947, give or take a year or so.
And, as we know for a fact that Sirius was the first non-Slytherin in the Black family, such a thing implies that Orion was a Slyth, and only a couple years younger than Voldemort himself. He would have known the man while at school, so that may have influenced a belief or action of his later on in life.
Tiffany definitely has a point on the marriage, in terms of it being arranged, as I can't really see a reason why second-cousins would generally consider any sort of romantic relationship normally. (Also, Walburga IS four years older than Orion, which in my opinion, is another piece of evidence on supporting a bit of an arranged marriage.)
However, perhaps there was a specific reason for that? I would find it hard to think that there were such few Purebloods in the '40s/'50s, when it stands to reason that they probably would have wed, but it's possible that, while there might be several Pureblood families that could have been chosen, either Walburga or Orion didn't think them pure enough, if that makes sense.
Looking at the Tree, once again, it doesn't seem like the Black family has a history of marrying such close relations a great deal. As a matter of fact, the marriage of Orion and Walburga is the ONLY one where two branches of the tree link up -- every other union is to an outside party.
Now, as for whether or not they loved each other? I can't really see them as getting strong in the romantic aspect of caring for one another -- they're only four years apart, and as second cousins, it can be assumed that they would have known each other fairly decently while growing up.
But, there would have been a level of respect and caring (I think) between the two. After all, their children *were* the only two sons of the Black family for that generation, so they were responsible for raising the Heir of the family.
All right, as for if there's something wrong with him? I, personally, don't really think so, but I do believe that he was more of a distant personality within the family. There is almost NO information known about him, canon-wise; you definitely have a point on that fact.
We can take Sirius's comments as evidence that Orion believed in/supported the core beliefs of the Black family:
"... my parents, with their pure-blood mania, convinced that to be a Black made you practically royal ..."
Although, that being said, I believe that he did love both of his children, Sirius more than Regulus, and especially when the first-born heir was young. The only time I've written Orion, as a matter of fact, deals with that, and it really sums up a good deal of how I've viewed his character. (It's in my Sirius-centric short story collection, called Shades of Black - Part II: Nightmares)
"... they thought Voldemort had the right idea, they were all for the purification of the Wizarding race, getting rid of Muggle-borns and having pure-bloods in charge."
However, while I see him caring about his children - they ARE the continuation of the Black family NAME, after all - I don't see him as being very overly, visually affectionate towards them, especially once they reach a certain age. The Blacks were definitely one of the "Status Pure-Blood" families, and not like people like the Weasleys, who really just sort of happened to be pure-blood. The whole "happy, loving family" wouldn't really apply, but respect/caring/loyalty/etc. would definitely apply.
I mean, the way that I've always seen the older, pure-blood families like the Blacks are those were loyalty to the family is THE MOST important thing - it really trumps everything else (even Voldemort), and as such, the scorning of those beliefs and a 'betrayal' of that regard (a.k.a. Mr Padfoot himself), is taken as a stronger shunning/scorning/betrayal than anything else.
OH, just got a thought while I was typing this :eek: .
As I was typing this all up, the thought came to me about why there didn't happen to be a portrait of Orion - or anything of his, really, save for a golden ring with the family crest - in #12. (At least, I don't recall there being anything mentioned.) And then, I realised that, according to the Black Family Tree, Walburga outlived her husband (by around six years or so).
What if Walburga had - for some reason - removed a lot of his things? Perhaps she had a bit of blame on him for Regulus's death, maybe? What if Orion didn't fully agree with the intensity of Walburga's scorn towards Sirius (my personal belief, though I don't have a grand amount of proof), and she became angry at him for not taking a greater offence at that betrayal of the family?
Here's a quote from my story that I linked to earlier:
I've already said (I think) that I don't think Orion's feelings towards Sirius, at least, ever intensified to the same degree that his wife's did, and I don't think Sirius ever had a grand deal in regards to hating his father to a similar degree.
A small smile came across Orionís face as he stared at the sleeping child on his lap, at his son whom he knew would one day grow to become a great wizard. Orion had known such a fact since the very day that Sirius was born; he had known the heir to the Black family would carve a place for himself in the history of the Wizarding World. He is already strong, the elder wizard thought. But stronger still he will become. A father always knew such things about his son, after all.
In short, I see Orion being sort of this more distant, strong-type individual, as a general person as well as a father. It may just be me, but I've just never seen Orion as going to the extent of hating either of his sons.
As far as him being political or something similar? My answer in that regard would probably go along the lines of Orion being just like any other pure-blood. (I mean, think about Lucius Malfoy in canon, and except for the actual "Death Eater" aspect, it could work for Orion.)
Ancient pure-blood families, like the Blacks, would have done the status games. They would have had donations given in the right places, had the right politicians' ears, etc. As Arthur Weasley said in OotP, in regards to Lucius:
Like I said, change the "Malfoy" to "Black" regarding Orion, and you can probably work the whole political-connection front well, in my opinion.
"Malfoy's been giving generously to all sorts of things for years ... gets him in with the right people ... then he can ask favours ... delay laws he doesn't want passed ... oh he's very well-connected, Lucius Malfoy."
(We do know that an Order of Merlin (for 'services to the Ministry') was awarded to Sirius's grandfather - it'd be either Arcturus or Pollux - after all. So, that whole sort of connection and corruptness would apply to the governmental politics.)
Now, we now that he wasn't an actual, marked Death Eater himself, as per Sirius's words. And as for the support of Regulus, I'm being quite technical, but Sirius is just making an assumption - however strong and justified it may be - that his parents supported Regulus's decision whole-heartedly:
It is possible that Orion wasn't as thrilled with Regulus's actions as Sirius's assumption made it appear.
"But I bet my parents thought Regulus was a right little hero for joining up at first."
(After all, like I said earlier, Orion was a contemporary of Voldemort while at school - and Walburga, too, for that matter - and it's possible that he found out Voldemort's Muggle ancestry, which could have impacted a view/decision of his or something?)
In terms of paranoia concerning his protections of #12? I don't think it was quite paranoia as it was just simple protection. I think a lot of the Wizarding homes would have some measure of security, and the older, more pure-blood a family is, it seems reasonable that they would seek to protect their home even greater than the average magical family.
The way that I personally see it, I don't think the Black home would have differed too much than how a lot of the other older, pure-blood families' homes were, like the Malfoys or Lestranges or others. (Malfoy Manor was probably unplottable and had some wards around it, after all.)
Also, we know that the Blacks were an inherently Dark family. Such implies that not *everything* that they did was on the right side of the law, and as such, demanded certain levels of secrecy and protection. (While I'm sure they could have bribed themselves out of any such trouble, it's better all-round if one doesn't even have to *mess* with bribing anyone.)
So, in my opinion, the fact that #12 was unplottable and had "every security measure known to wizardkind" on it isn't incredibly far-fetched or an indication of incredible paranoia for Orion.
(Also, keep in mind that the unplottable aspect of #12 keeps Muggles away from the house just as much as magical visitors. And I'm pretty sure that the Blacks would have wanted to deal with a Muggle sales person or someone. That, and the neighbourhood was Muggle, so they'd definitely have reasons for wanting to keep such - as far as they were concerned, filthy - people away.)
Whew! I'm exhausted after thinking all that up now! I hope some of that helped you out, though!