The process of creating skins for League of Legends involves, in most cases, the development of a alternative universes with their own lore separate to the overarching themes of Runeterra.
It's a practice that brings to life the ideas of the artists, and that can give rise to new themes that complement the story. This method has proven its efficiency on several occasions, the most recent example being the launch of the Chaos and Order event coming soon to the game.
The skins born in a Riot contest
In the case of the Arcade family of skins, the Demacia Vice line emerged as an alternative.
Garen and Lucian benefited from these parallel universes created by the developer, which came with a simple pretext -- they both starred in a game with the same name that existed within the Arcade skin universe. It was widely played by Ahri, who holds the points record in the game.
What many players may not know is that Demacia Vice is in fact a title that actually exists. It was born of a contest called Riot Thunderdome, a game jam within Riot in which developers have a limited time to create a game.
Riot hosts the event to allow developers creative freedom, and from which a few ideas have been crafted.
As skins are little more than add-ons bought by some players, it's easy to forget their relevance or assume the creative process is lazy.
However, this proves that Riot make their choices well, evidenced by the variety of content that comes to League of Legends. This is backed up by strict quality control, meaning little is fully cancelled.