I love twins omg (thought i posted this is a delirious haze this morning when I saw the title, was highly confused for a few 'cause im working on twins too right now )
Okay! Michael. What a darling, first off. I love that his friends call him Twin One, but it's sort of strange that he doesn't have any other nicknames - Mick/Mickey, Mike/Mikey, etc. Does he insist on being called Michael? It's really neat that you went with a redhead that has brown eyes - don't think i've ever seen the combination on here before (even though that's like, a lot of my characters whoops ^^; ). And the freckles! But you mention one of his motivations is protecting his brother, which makes me wonder if something's wrong with Matthew?
Predicting the weather is a super cool talent though - is it through intuition or did he study meteorology in his free time? Can he smell rain coming? (that's a thing, yes!) You could probably stand to add a few more mannerisms, does he do anything unconsciously as he's talking? How does he sit in chairs? What's something he's constantly got in his pockets?
I love the backstory, too, but you don't make any mentions of what threw them into the other universe and I'm super curious about this.
Onto Matthew! Matt's a super common nickname, so that definitely fits. How does he feel about being called Twin Two? Does he have astigmatism (makes everything super blurry, sucks bad) - if so did he need glasses as a kid? The mannerisms here could also stand to have a bit more information - how does he talk? How does he hold himself? I love that he's super shy and quick to judge, which is so very different from his twin! Was he bullied often as a younger kid because of it? I also love that he plays as sort of the peacemaker/mom friend of the group as well.
His politics are a little confusing, to be honest. What sort of views is he mixing? With his favourite colours being orange and purple, does he enjoy Halloween? What sort of books does he love - ones related to photography, nonfiction, fiction, etc.?
Overall, I think you have some very solid characters so far, which could use just the tiniest of touch-ups to clarify certain things. Good luck with Endera, and hope some of this rambling helps! ^^;