Hey, sometimes the GM needs backup when having a game session.
Tell a story of either being co-GM or being the player facing the co-GM.

In my group, I'm the person everybody goes to for anything mechanical. So I'll often be asked to help design dungeons or encounters for the actual GM, essentially making me the co-GM of my group. If I'm NOT the co-GM, I'm the GM, so I'm doing that stuff either way.

I also often make entire characters for some of the other players in my group, but that's only because I can bust one out in 10 minutes and have it be great.

Our group reached the point where one of the DMs decided the more expedient way to do combat was to just split the party in two and have each group fight half of the enemies without interfering with the other. He'd handle one group, and I'd play the enemies for the side with my character.

I also joke that I have the player's handbook more or less memorized (I don't, not all the details), so if there's a rules or mechanics question, I can usually give an answer, an educated guess, or at least say where it's mentioned in the PHB.

Trust me... you don't want the story of the last Co-DM I had to deal with.
The one time I was Co-DM was for a friend's first time DMing, where I was mainly in charge of running combat for her. Meta-gaming munchkin ruined it on the second session after missing the first.

Even out side of the quartermaster bit, you always listen to the subject matter expert (SME) and as this is both a weather issue, and a nav issue, that's Nat. You can be higher ranked, you can have more experience (in general) or a thousand other things. In their element the SME is god.

In my group, I'm one of the people that's got the books, so if we need to quickly search for a specific monster, or item, I'm usually pulling out the books to help speed things up.

DM knows I'm good on not meta-gaming, so it's cool.

Sleeping... Any story about everyone in danger and yet one character is sleeping?

I *tried* to sleep through danger one time... my character was a warlock and we were in Strahd's castle (playing the Curse of Strahd module). I was out of spell slots and we'd found some candles. I figured with wax ear plugs, I could try to sleep for an hour and let the rest of the group protect me. Sadly, the GM wouldn't allow it.