Naturally, it's time to ask about Vlad.
As the Varus comic pointed out, blood magic finds its origins in the Darkin. This wasnt explored in depth in the Varus comic beyond mentioning, and it wasnt explored during the Swain VGU/Noxus Update.
Nor was Vlad himself, at all.
Something I personally like a lot is that a lot of the lore - both actual events as well as character interactions/dynamics - is actually revealed through VO updates. People comb through the latest release or re-release for whatever little tidbits of storytelling and insight into certain relationships. It's an interesting approach, to say the least, and I commend Riot for it.
I can only hope they'll extend this to Vladimir, who gets...remarkably little in terms of interaction. There wouldnt be a better time in the foreseeable future (now that Swain has come and gone without any direct quotes to Noxus's haemomancer) to give us some information on blood magic, how it was transferred from the Darkin to humanity, and insight on how Aatrox views the whole ordeal.
~~and maybe even some characterization for our favourite blood mage~~
It's something I'll personally be holding out hope for.