Ideas:

MLP The Faithful Students
Before Luna was banished to the moon, both she and her older sister had a personal student, people like starswirl destined to greatness and also people Celestia and Luna tried to prepare to take on the mantle of alicornhood. While the objective was the same, it still was ultimately a competition between the two. So yeah, some or years depending on how we scale things before Luna went batshit insane, the new students roll in to first face challenges like Sumbra, changelings, discord and eventually each other. I did this formula previously and we established, for fun, that it was best for one person to play Luna's student and Celestia while the other did Celestia's student and Luna. I'm particularly fond of playing Luna I'll admit.

Mass Effect
1: Mercs in the terminus system that disobeyed Omega's first and only rule.
2: Group of do-everything corporate or secret government soldiers & scientists that was charged with recovering pieces of reaper tech around the galaxy but have a run in with the Leviatans, now, they know too much while they themselves barely understand it all.
3: Pre-reaper war explorers that explored an unknown sector of the galaxy, unknowingly stepping on reaper leftovers of the last cycle.

How to train your dragon
Little did Hickup know, that damn huge dragon acted like a king for them and while a king is demanding, a king organizes and protects its vassals and subjects. Without it, the dragon population began to separate itself, be disorganized and fade away. Decades after this the village that domesticated the beasts is a legend and the dragons are extremely rare, but this isn't what's worst. Viking culture is disapearing, or rather is being wiped away. Crusades from the so called civilized lands, missionaries converting the population to their singular god, the vikings are in need of a ruler. I'm saying either a dragon and its rider or two friends that go on the adventure together. Saviors of the realm while being hilariously evil barbarians burning rome to the ground for the southerners. I say we can do it like the MLP thing, one playing a character and the other playing our partner's dragon.