: Johnson is just trying to help his dead friend's daughter through life.

She couldn't kill Johnson when push came to shove. It could be because she couldn't kill her "uncle" but, in fiction, this is usually read as, "they were in love".

The chaste interpretation can't be ruled out but it is extremely uncommon in fiction.

And Johnson does have form.

Having said that...

He did say that her father never asked him for help either. https://youtu.be/Fwn6h6vofOE?t=1934 which is a pretty weird thing to say unless he and Keyes were friends. I mean, why on earth would a ship's captain ask a marine for help? Help for what? Help running his ship? Help putting on his shoes? There doesn't seem to be a lot of scope for a ship's captain to ask a marine to do anything that would help the captain (not personally - obviously Keyes could tell Johnson to do something that is part of Johnson's job but that's not helping Keyes).

Why would a marine be offering his help to a captain? How often could a stranger marine offer and be rebuffed b4 it became weird. :-)

That still leaves the question of how and why they became friends - their respective jobs and career paths seem to mitigate against that. Is this covered in the fiction?

Johnson is too familiar with higher ranking officers. I suppose that this is because Johnson is an awesome character in the game and we just can't get enough of him. But Johnson being pally with ship's captains doesn't really work for me if I am thinking of the Haloverse as a real place.

I can see it working better with the Chief. Although Spartans are generally aloof but Johnson might be a Spartan 1 and might have trained or worked with John on other occasions.