Stranded with the above poster

Nathzu would attempt to set up a camp on the island, used to sleeping rough anyway, putting aside differences with the human, except maybe filling his helmet with sand.
Knowing nothing about Nathzu, I can only presume it would be a fairly cordial affair where both Elves would work together to survive and hopefully come up with a means to return to Quel'Thalas. There doesn't seem to be anything to suggest otherwise.
Mostly just use his military training to survive on the island and co-operat with Cathrion, hopefully well-enough. They'd eventually come back to Quel'thalas and either part ways with a bitter view on one-another, or just start hanging out. You never know with ol' Veg.
Would build a parasol and sit on the beach and then let Veg do all the surviovry things. "Just shout if you need any help with anything, meanwhile I'll just sit here and look pretty!"
Putting up a rescue fire to lure a few more people's there so I could make a portal home to Silvermoon fir me and the rogue
Kill him and eat him to prolong survival, LOGIC!
Murder her in the wake of her first attempted cannibalistic session, then fend for herself.
Work along with the elf if she would allow it. Using what he knows about the kind of island it is to their advantage.

would imagine some tension as they would have some disagreeing about how to get along, but nothing lethal. They would survive long enough to make an escape plan, or being saved, and then part ways, maybe seeing each other on the battlefields of Azeroth.
Help hexul get enough supplies to survive walking across the water for a week or something like that and then start wandering across the water by freezing it. "Escaping this island couldn't have been easier.."
Build a very very very tall tower and then cast slow fall on the both as they hope to find civilization. If the tower wasn't big enough. She'd get the elf to freeze the water for their landing.
Ask for a portal to Stormwind.. oh and some conjured cookies! While I'm playing with my succubi ( ͡° ͜ʖ ͡°)
"Trifling gnome. Your arrogance will be your undoing."

With those words, Tethenar would abandon the lazy Gnome to his succubus on the island, and instead do everything himself to allow for only him to leave and return to Quel'thalas.

Oh, and he may kill the Gnome at some point prior to leaving, depending on how hostile the Gnome turns out to be.
This would be an interesting enough scenario, actually. I believe Seth'ranis and Tethenar would work together without many qualms at all, but Mage would probably aggravate and provoke the Blood Knight in a mild manner due to neither of them sharing the same sense of humour, interests, or indeed, moral code.

In spite of (probably) not being able to use his powers. Seth'ranis would be crafty enough at coming up with suggestions to aid them, and even display some decent "sans magic" styled abilities, but at the same time, probably do as little as he had to while allowing Tethenar to do most of the heavy lifting and the likes.

So I'm thinking it would be a successful enough kind of partnership laced with thinly veiled insults where they realise working together is certainly for the greater good, then when they return to Quel'Thalas, departing with slight bows never to bother one another again ... at least, not until Tethenar finds Seth'ranis hitting on some female relation of his.

"Oh come now, Tethenar ... you were lucky enough to spend weeks on a desert island with me, won't you afford her the chance to bask in my glorious company for just one night? Jealousy is a terrible thing!"
Jack has a great dislike for elvenkind that not even he knows the origin of.

Be it Night, Blood or High; he probably dislikes them.

This prejudice would inevitably lead to conflict-- a conflict that Jack will more than likely lose.

Fighting is hard with food on the brain.
Upon realising he's a Worgen, Goldy would violently attack him, likely killing him. She would then go about attempting to take care of herself ...

... this would either result in her dying through not being able to look after herself properly, or, when eventually found by others, it would turn out she's reverted to some primal animalistic like feral state.
Deciding for once to avoid the tired cliché of joining forces against a greater peril with a horde member, Khelissa would say something a long the lines '' You are my enemy, prepare yourself'' before engaging in combat with said goblin.
Gral'nok would work with the warlock until seeing hostility, in which case, he would proceed to attempt to violently punch her skull. "YOU IDIOT. YOU MORON! WE'RE AT PEACE! BECAUSE OF YOU THERE'S GONNA BE A FOURTH WAR, IF YOU MAKE IT BACK TO ANYWHERE!"

The orc would pant heavily after shouting, sinking to his rear, and... almost sobbing?
"All that paperwork, for nothing."
Be somewhat friendly since there's a treaty, but keep an eye out, his armor gives off a slight aura of "Me smash", you'll never know..
Happily greet a fellow member of the Alliance and share his knowledge of fermentation. If it's a desert island then coconuts are good for it, if it's a craggy/rocky island then find some seaweed, boil off some salt-water, ferment the seaweed, use the crystallised salt from the boiled off water and have a seaweed slammer.

Uh, you are the kind of monk that heal, right? Because we'll probably need it.
He would stand there, staring at Grif. Not saying a word.
After several minutes of awkward silence, the unliving tauren would abruptly hug the human and run into the sea yelling "NOW WE GO BACK TO NICE PLACE, ME DON'T LIKE HERE!".
Unfortunately Meat can't swim and his armor doesn't help.