So ima just dig right in with my theory and yall can give your thoughts. I might be grasping a little or clinging onto vague ideas but I like the theory so I might as well post it.
Base allomancy comes in a set of 16 with subsets; Push, Pull, Internal, External, physical, mental, temporal, and enhancement. pretty basic allomancy knowledge, right? but we also know that every god metal can make their OWN allomantic sets, with atium alloys as our proof. the 11th metal (gold and atium) and the atium mistborn burn (atium and electrum). now usually there wouldn't be much for me to build off after that. each god metal is another set of 16, how could we possibly figure out what each power will do without knowing something like the subject of the powers, like physical in the base set. except we DO know one of the subsets for ruin's set of allomancy. and its the same as the base set. in fact the powers are nearly identical, except for one key difference. they have switched from internal, to external. gold is an internal metal, so is electrum. but their atium alloy counterparts aren't. the 11th metal lets you see other peoples past(or potential future still not sure) selves. but gold lets you see your own past/potential futrue self. nearly identical powers, except for the fact that the subset has flipped. so here is the theory. are ALL the allomantic powers in ruin's allomancy, simply the same power with a subset flipped? how would that translate into powers like tin, or pewter? or duralumin? we already have a power that essentialy works the same as duralumin, except it is focused externally. its already a thing in base allomancy. is it simply a fluke? a coincidence? or, does this perhaps work like the power overlaps in the knight's Radiant orders? they share power types across certain orders. are we maybe just seeing something similar to that? do ruin and preservation simply share an allomantic subset, changed slightly to fit them? or is it even less than that, just sharing these two powers, used in separate ways, because i cannot fathom how you can use time bubbles internally. or is it something else yet again? does ruin have external powers, and then a different subset, that isnt internal at all?
Sorry, I know thats a lot more question than theory, but Its been scratching in my head for a while.