teaat2am:
only half a prince
Has this been done before? I’m sure it has.
There are a lot of parallels between Loki and Snape I think.
Paddfoot, Prongs, Wormtail and Moony
I need 7 more books on The Marauders
That’s 7 years of their lives in Hogwarts, each titled “The Marauders and The…”
Oh the joy of parents generation.

There is no canonical answer to this question. We can only speculate on Sirius’s frame of mind at the time when he wrote the will. We don’t even know when he wrote it — perhaps he wrote it before Azkaban. Harry was his godson, and one could argue he had no plans for a son of his own. (Now, he may not have had Grimmauld place pre-Azkaban, but if the will simply stated Harry was to have everything, it wouldn’t matter when Sirius acquired what, only what he had at the time of death.) Maybe he wrote it during OotP, we don’t know.
Sirius might have intended to leave his possessions to someone of the younger generation, someone who, given the natural course, would outlive him significantly (unlike Remus, who was the same age). True, there was always a war on — he was imprisoned for the time between the wars — so he knew he might die prematurely. True, you can list more than one person in your will: you can say, if this person is alive, them; if not, this other person. However, Harry was more likely to be killed than anyone — everyone knew he had a serial killer after him.
It wasn’t about that. It was a gesture. That’s how I think of it. The will wasn’t about possessions or money, it was a gesture to Harry, a last gesture. He knew something might happen to him, and he knew that Harry had no one else, so Sirius wanted to be able to give Harry one last thing if he was killed. The way that Sirius thinks, that one last thing had to be everything, that was the only way to make it significant.
Lastly, for the sake of the story, Kreacher needed to answer to Harry, and for that Harry needed Grimmauld Place. So, Sirius had to leave Harry everything — he wasn’t going to leave him Grimmauld Place specifically because he hated Grimmauld Place, and he loved Harry. So, while Remus’s name in Sirius’s will would have been evidence for a romantic relationship, it’s absence is not evidence against it, it’s simply neutral, it’s part of the cogs which run the story.
Werewolves are under such heavy Ministry of Magic regulation (registration, difficulty holding down jobs, classification as Beast most of the time) that it stands to reason that they can’t inherit property. That was always my understanding of it. Remus can’t inherit anything of Sirius’s because even if there’s no specific rule against it, there’s undoubtedly some third cousin twice removed (perhaps a Malfoy) that would challenge the inheritance of Black money by a ~mongrel, so it’s easier to just give it to Harry.
Also, to delve slightly into romantic head!canon, Sirius always assumed they would die together, so there wouldn’t be a reason to need to leave Remus anything.
Werewolf laws are definitely strict (damascened brought this up too; sorry I can’t reblog you both). It’s possible that 1) they aren’t legally “human” or “wizard” and 2) one must be legally “human”/”wizard” to be cited in a will. I can’t see a law directly prohibiting inheritance by werewolves, but who knows?
I’m with you on your second point. I don’t imagine he literally believed, “We’ll die as one.” It was a more tacit assumption that he never thought about, but which made it extremely jarring whenever he thought his Moony might be lost.