Most fan missions have you playing as Garrett. This is fine when the mission is simple, the story is light, and the situation typical. But if your mission is plot intensive or presents an unusual situation, it may be time to consider inventing a new player character (pc) for this mission. Speaking in broad terms, you have three basic options.
The first choice if obvious; the default if you will. The second choice presents a bit of a problem; unless you specifically give the pc an identity, the vast majority of players will simply assume that they are playing Garrett. Because of this precedence, the second option is not really a viable option over the first.
So, what are the advantages of having the pc be Garrett?
But what are the disadvantages?
If you want to try to create a new pc for your fan mission, ask yourself the following questions.
How is my pc different from Garrett?
How will I convey to the player that my pc is not Garrett?
Where does my pc come from? Is their back-story for only me to know, or do I need to explain it to the player?
How will my pc’s personality have a bearing on the types of objectives I give?
Is this pc not as skilled a sneak as Garrett? How can I change game play to reflect this?
Does this pc use different tools than Garrett has?
Should I find a voice actor for my pc first and allow them to help me define who my character is?
How can I allow the player to take ownership of this pc without them forgetting that they aren’t playing Garrett?
A pc doesn’t have to be anything like Garrett. It could be a disgruntled Hammerite novice, or a down on her luck prostitute. It could even be a drunk baker who just realised that he just spent all his day’s income on ale and when he gets home without bringing any beans for supper his wife is going to kill him. Have fun.