Join the discord here!
You are welcome to make a custom character for crusader king games as long as it does not replace one of the main characters. If you're unsure message the organizer of the event or open a ticket in the discord. With character creation it is expected you actually take the time to make an interesting person who has flaws as well as strengths. Remember that in roleplay it is not the strongest character who makes the best story, but the most varied one.