Just for the record, Neon and Tesla are officially a married couple. Their wedding happened in some Japan only material in relation to some event IIRC.
I'm pretty sure Mary would like to get it on with M, but M is too fixated on A.Z.T.T. to care, even though Mary is special to him (before Sharnoth came to pass he just took notice of her because of her Golden Eye, same as Ati. Which is, surprise, something related to A.Z.T.T.). A and Lily's relationship is analogous to M's with A.Z.T.T. , so more "romance" being involved is a must. Like a princess and her knight in shining armor.
"What a Beautiful Memories" has more to do with the game's plot other than Refrain's effect of memory loss on Sona Nyl's inhabitants. But I'll leave it at that. Also, Edison has a final "**** you" button for Elysia and Lily. ****** has to close up an experiment he's already bored with in the most sadistic way possible after all. And about that org that follows him, Henry Ford's a member, and he's S C A R Y.
About stuff that was talked about earlier... Sekime were not natural to Golden King, nor to anyone that's not Tick Tock Man or M at the very least. They are a side effect of bodies getting modified by the Cracking Effect, which also grants some of their eye sets power. Example of powerless Sekime owner: Kia from Inganock. However, Hilde from Valusia or Rosenkreutz surely have powerful eye sets. About Thoth, yeah he's an enigma (Valusia's WN does drop some heavy hints about a possible relation to A.Z.T.T. by naming his Caspar Body Azathoth). His Melchior Body is what shows up in Valusia as Toto, and given this body's a shapeshifter, it can show up as whatever. Thoth didn't create the bases for WIC, Golden King did. Thoth dunked on him so hard in the past he put himself under his command, and the organization he led was remodeled into current Society/WIC. Thoth however doesn't really give a **** about the objectives of his subordinates, he's got a hands off approach to running the organization (from Rome, using his Balthazar Body as his representative), so WIC mostly relies on Acting Leaders (Golden King most of the time, Professor/Moriarty during his absence till Gahkthun happens). Machine Lord and Hilde are both Golden King's subordinates, yes, and I'd assume he's stronger than both. Valusia's portion of the Fullvoice Fandisk shows Golden King in one of his terminals issuing orders to Hilde (no CG of him though), even.
Tesla was just left to rot inside a Time Prison, no need of going any further. About an eventual M vs Tick Tock Man fight (given they are active enemies, it might end up happening)... I'd say Edison has the edge for now. Even if M did say in one of the Sharnoth stories of the Fullvoice Fandisk that they have the same power, I presume he meant without any external buffs.