It's nice that UltraBoy and Phantom Girl get to remain a couple for most Legion reboots, but it's kinda sad that we don't get to see them in a quartet with Mon-El and Shadow Lass as much as they did in the past. Mon-El and Ultra Boy had a shared history with SuperBoy and grew more close with each other down the line. Shadow Lass and Phantom Girl are the best of friends. Dated tropes, cheesy couple stuff, silly double dates, and BAD reboot writing choices aside - I liked the idea that the whole group could've had some unique and fun dynamics within the Legion.
Half of this is basically headcanon, so take or leave whatever my impression of what is or isn't accurate with whatever helps makes it work for you. I'm just putting my thoughts down.
Mon and Jo are bros. They've relied on one another longer than their time in the Legion and should be in sync during a tough fight or just dealing with mundane life problems. And while both boys wear red, Mon-El is the blue-oni to Jo-Nah's red-oni.
Tas and Tinya are BFFs. They talk about everything and shouldn't be afraid to ask for help or step in when the other is going through a bad time. Tasmia is always offering to get people out of thier comfort-zones, but Tinya always is the one who comforts Tasmia (Or snaps her out of something) when something weird is going on.
Tas punks on Jo. Jo tries to punk her back. Shadow Lass approves of Ultra Boy, but would never tell it to his face. Ultra Boy probably wants her approval more than anybody - and not just because she's Phantom Girl's best friend and Mon-El's beloved, but because of his rough past and wanting to prove he's worthy of being in the Legion and his friends.
Mon and Tinya vibe with eachother - Sometimes they are on a level where words don't even need to be said. With Phantom Girl's powers, she must have left some kind of impression on Mon-El, who has a traumatic history with the Phantom Zone and anything adjacent. Phantom Girl has also been personally responsible for saving Mon-El from the Phantom Zone more than once. Mon-El has to have strong sense of trust and appreaciation towards Tinya, all things considered. Tinya must pretty patient with people - especially if she's known for dating Ultra Boy, of all people.
