From Elwiki

Yo, call me Ullein. Decided I might as well not have a red name. I'm a casual player and you might catch me on the NA server as Ullein (L42 Time Tracer as of last edit). I'm mainly here for the lore.

Here's some lore on this wiki: Elsword_World, Story/Ruben Story/Elder etc., Quests/Class_Change (the last of which really needs help)

And some more lore: Dungeon clear quotes Babel lore tag

And finally, you can rewatch the character's intro cutscene from the bottom right "Prologue" button in the channel select screen.