HoYoLAB is the community forum for Genshin Impact and Honkai Impact 3rd, with official information about game events, perks, fan art, and other exciting content.
SevyPlays: What's New with Itto? Artifact, Weapon & Team Updates
How Cookie Run Bakes its Monster Revenue — Deconstructor of Fun
Love Letter Fictional Character
Game Design Fundamentals
Liyue Character Templates by MarsKatt by MarsKatt on DeviantArt
openFoamUserManual PFM, PDF, Class (Computer Programming)
House of the Hearth, Genshin Impact Wiki
Genshin Impact: The Wanderer / Characters - TV Tropes
as per request: character relationship chart (+ a version with coloured lines to maybe make it a bit easier to look at) : r/Genshin_Impact_Lore