This is what I know so far:
The Quartermaster is a primary figure in the Valkyrie storyline, supplying the Valkyries (and maybe the Schizm) with supplies and technology (though https://soundcloud.com/ccpgames/eve-valkyrie-an-echo-from-a-quartermaster seems to suggest he is working against Fatal now. The Source was the Drifter tech)
He was rumored to be trained by The Rabbit, a tech genius who invented the brain kidnapping device used to catch Valkyrie pilots, and resurrected Fatal.
He is connected to the Agency, insofar as he was the person frontrunning the Agency event: Warzone Extraction.
He has a vested interest in Drifter Tech.
He hunted after a secret Thukker base to get coordinates to a Drifter Hive to steal their technology and augment the Valkyries.
He also collected untold numbers of Corrupted Trinary Relics from capsuleers during the Warzone Extraction Event.
He ‘doesn’t take sides’ but he does ‘takes orders’
He is described as a snake and a thief. A dealer in secrets, and someone that everyone knows, but no one has seen in person.
He admits to having spent years moving pawns to get access to the Drifter Hive, implying he knows more about Drifters than many.
The Agency is a property of the Ostrakon Agency and Intara Direct Action private military contracting corporations. https://community.eveonline.com/news/news-channels/world-news/scope-network-ownership-formally-divests-capsuleer-job-brokering-business/
The Ostrakon Agency is a dust era Gallente merc corporation that saw substantial success during the Jin-Mei Civil conflict and has obviously been doing quite well for themselves.
I thought I remembered him mention he worked for a ‘consortium’ However I cannot find it now, and it appears the Quartermaster started actively just prior to the announcement of Upwell.
That’s what I got, did I miss anything?