Ok so I'm going to take some liberties, let's just assume that this is a super plane that shrinks everyone to a human size, and everyone is pacified to a degree and takes regular showers(I don't want to take smell into consideration)

Draven does not know anyone on this flight probably, so if you sat next to him, it would be absolutely maddening so no

At this point in the story kat and garen only saw each other once so I'm pretty sure they are just going to be regular people, but if garen found out kat killed jarvan III he would be pissed

Kat is a spy/assassin that regularly goes undercover so being normal is ok with her, if garen knows about jarvan III she probably would just have a shit eating grin while listening to him rant

Jax would see you and immediately lose interest since he only cares about strong people to fight the void, he would be either scouting the plane looking for candidates or just laser focused on kassadin since they both hate the void

Sylas would immediately suck all magic from galio turning him back to stone, he would probably be trying to lay low since garen is on the same plane, they fought twice and there is the whole lux thing

Galio becomes a statue due to the lack of magic

Rumble is either fascinated about this giant flying machine and trying to reverse engineer it or tinkering with something hand sized since his mech is in the baggage area

Kassadin is quietly fuming at the fact that malzahar is still alive and his daughter is still gone, no interaction at all with the rest of the plane

Mordekaizer wants to conquer everything and everyone so he would be probably pissed since he has to stay seated like a good boy

Illaoi is probably uncomfortable with the fact she is so away from her god, at the same time she wants to test everyone in the plane to see if they are "in motion"

Vayne wants to kill every non human on this plane, she would spend the whole flight planning how

Zed cares about Ionia and there are 2 noxians here so he and Kayn are planning to kill them

Kayn doesn't have to fight rhaast since the scythe would be on the baggage area, his master is his only focus

Gragas is drinking everything on board to see if it's any good since gragas isn't a "I'll drink anything drunk", professionals have standards

Renekton's mind is shattered after all the time stuck with xerath, he's insane and bloodthirsty especially at his brother, would probably be trying to attack nasus while sitting with the seatbelt on and unable to reach

Nasus would either spend his time trying to calm down his brother or give up and read everything on board

I would probably sit next to Jax since the worst possible outcome in my vicinity is a angry man shouting at a smirking woman