The amount of love Robert conveys to Fitzjames in his letters makes me emotional every time. Fitzjames was so fortunate to have a father who loved and supported him like this. I think about how it's for the best that Robert wasn't alive anymore when Fitzjames went missing in the Arctic... it would have killed him.
The way to tell Lieutenant (N)Edward Little and Lieutenant Henry Collins apart is by the two distinct types of terrible time they are having.
Little is clearly in the wrong universe with the wrong level of responsibility, he should have been born 150 years later and been a Little League coach, standing on the field saying things like “Good hustle, guys!” The fact that he happens to be a Naval officer in the Arctic is an accounting mistake and you get the sense that on some soul-deep level, he knows this and is haunted by it.
Collins on the other hand would be having the exact same terrible time in any universe. I can picture the guy having the same reaction to having to find a parking space at the mall as he does to any of the canon events.