Michael Trewartha's Instagram is here:

https://www.instagram.com/michaeltrewartha/

He used to produce under the alias "SIRIS" but deleted all traces there. He has more of those LA rooftop pics. Fun fact: he used to work at Menchies ice cream when he was 18

He is indeed Singularity's brother, and took some official photos of him as well back in the day, and he takes similar photos of himself:

Singularity pic: http://www.dancerebels.com/wp-content/uploads/2012/10/Singularity-Highlights-The-M-In-EDM.jpg (pic credit to Michael Trewartha on the blog post)
Michael pic: https://www.instagram.com/p/MO2MJKoYK1/?taken-by=michaeltrewartha https://www.instagram.com/p/ML7Tx8oYKg/?taken-by=michaeltrewartha

He also uses Ableton like Grey does! https://www.instagram.com/p/c0UNTlIYFj/?taken-by=michaeltrewartha

He made a behind the scenes video of that Grey photoshoot: https://www.youtube.com/watch?v=-81AEWuC3M8

Proof that he's Singularity's brother is also here with a childhood pic of he and Kyle posted on his Instagram:
https://www.instagram.com/p/MJ3dSFIYA9/?taken-by=michaeltrewartha

Meh I guess I'm going a bit far but all this is public info, I'm just connecting a few dots here

haha i love the mystery of it all. Those are the best right now though, that papercut remix holy shit

The Disarm You one though holy shit

I have no idea who they are, but their remixes are really incredible. They have to have some experience with being a dj because this sound is just so clean.