Honestly, it may depend on what group you're going to be joining up to roleplay with, but from what I've seen a good rule of thumb is to make sure that your character's background doesn't have a specific influence on the plot and characters of the main scenario. An easier way to remember is that if the role or position you want to make your character for has more than one or two nameless and faceless people in the canon lore, you should be fine putting your character in that position.
For example, people might frown upon you declaring that your character is Cid's daughter, because you're attempting to put yourself in a position of explicit influence in the life of that established character.
However, you'd probably be fine creating your own noble family in Ul'dah because in the story, the vast majority of nobles are basically nameless and faceless. The more nameless and faceless positions in the group, the safer you'll be in joining it.
Now, that doesn't mean your character can't have any influence in the world, it just can't be explicit. For example, most of my characters come from the Adarest, a group of pirates that hate Limsa Lominsa and are always trying to attack the city. I'm pretty much okay in doing this because Limsa is always under attack from pirates of one form or another, but they are a bunch of nameless, faceless pirate groups.
Having an immortal 10,000 year old character who is a vampiric werewolf is frowned upon for possibly different reasons.
For example, people might frown upon you declaring that your character is Cid's daughter, because you're attempting to put yourself in a position of explicit influence in the life of that established character.
However, you'd probably be fine creating your own noble family in Ul'dah because in the story, the vast majority of nobles are basically nameless and faceless. The more nameless and faceless positions in the group, the safer you'll be in joining it.
Now, that doesn't mean your character can't have any influence in the world, it just can't be explicit. For example, most of my characters come from the Adarest, a group of pirates that hate Limsa Lominsa and are always trying to attack the city. I'm pretty much okay in doing this because Limsa is always under attack from pirates of one form or another, but they are a bunch of nameless, faceless pirate groups.
Having an immortal 10,000 year old character who is a vampiric werewolf is frowned upon for possibly different reasons.
