Old lore did it better there. Yes, I know, old lore is not chanon anymore, mimimi. Just saying.
In Old Lore Fiddlesticks was created by a summoner, but after he got alive he went on a rampage and killed everyone. That's it. They locked him in the room.
Skarner was part of the Brackern, or still is, and lived in Odyn Valley. Their race endangered when the runewars started and they dug themselves underground. Odyn Valley became the Crystal Scar, which is, as far as I know in Shurima Desert now, and Skarner was the first one to check out the surface, to look if the world still would be too dangerous for them.
But this all is old lore and doesn't apply anymore, but still I think it's easier to understand the Champions if you know where their story began when they came out.