i feel like the marauders only are the marauders because they were all in the same place at the same time, like i cannot imagine remus and sirius becoming friends or peter and remus being friends at any time, the valkyries too, do you imagine loner rockstar marlene and pretty girl mary to be friends in their own way?
sirius would have only noticed remus and falllen in love abound 4th year, and only said that out after he got disowned. and peter and remus would be friends in some other way, like they would study together, but their entire dynamic of being fun and doing pranks is because of them being in the same room as sirius and james.
also, all of the cross-relationships ( dorlene, pandalily, petermary, jegulus) they all became what they are because sirius was a connecting factor- he connected the slytherins and gryffindors.
i feel like they are so intercoonected to each other-in a souls linked way, that everything that happened to them is because of each other. they lived for each other and they fought for each other and died for each other.
if the gryffindor house system was a little bit more different, i feel like they would have hated each other and lost the best parts of their life for it.
( except for moonwater and marylily and also any james friendships, they would all be pathetic and rosekiller, the others would have done hogwarts alone, and its very sad.)