Uncle Al

It would have been interesting to see some backstory on how Henry decided to settle where he did, and his connection to brother-in-law Al.

There was a scene where Al told Ketchum "You have no idea the hell storm you're about to let loose".
This seems to indicate Al either knew exactly who Henry was, or at least his former status as top-notch gunslinger.

However, how would Al know this? Henry seemed very tight-lipped about his past.
Imagine he moved to this area, met his to-be wife and brother-in-law. When would he spill the beans? That would seem too big a risk until he knew them well enough, and once he did - why risk rocking the boat?

I came up with my own backstory to fill some of the gaps:
The farm where Al lives is where Pat Garret grew up along with his siblings - Al and Marie(the future wife of Henry).

Henry was friends with Pat(I read this is historically accurate), and at some point in time he visited the farm. He met Marie, they fell in love and soon they were getting married with a child on the way.
Pat and Al might not have been too keen on their sister marrying an outlaw but they could not let her child grow up without a father either.

That is why Pat took the risk of faking Henry's death, after which Henry settled with his new family in the area near the Garrett homestead.