So I was just thinking about the Gray-Manes, all of the younger ones are Eorlund's children but we see nothing of children had by his brother Vignar. Vignar is a long standing member of the Companions, so if he did have any kids I'd imagine they'd also become Companions. Arnbjorn in the Dark Brotherhood Sanctuary is definitely a former Companion, and he has gray hair, just like all Gray-Manes. Could he be Vignar's son? or perhaps a younger brother to Eorlund and Vignar?
Just an interesting theory I came up with, probably not true, but it's something interesting that I wanted to share! What are all of your thoughts?
I could never really understand the ages of certain people, and with the Gray-Manes it gets even trickier because they all have gray hair regardless of age. Vignar looks pretty ancient though, that's why my first instinct was son, but who knows?
I suppose it would make Astrid a Gray-Mane by marriage, though Arnbjorn probably would've dropped that title once he joined the Brotherhood.
you may be right however you said he probably wouldn't have dropped the grey-mane title. but the tradition of the dark brotherhood is that you leave you past behind to join a new family. So the grey-manes are no longer his family and the dark brotherhood members are his new family therefore he might of dropped the title making your theory valid