As a GM you are going to want some of your plots to resonate on a more personal level with your characters. The grand adventure, saving the city/world, is all well and good, but sometimes you want the problems from home and life to come up. Where to start when you want to do this then becomes the problem. After all, you may want to build a plot around Sarah's barbarian, but how do you do it while still engaging the other four to five people (or more!) sitting around your table?
Backstories Make Great Places To Begin
If your players make backstories then that is a great place to begin looking for hooks and ideas for personal plots. Back stories tell us where the character began, how they received their training, and why they're out in the world adventuring. They also give some of the low hanging fruit used to construct basic plots such as family members, old enemies, and things of that nature.
A lot of games - such as D&D 5th edition, Shadows of Esteren, and Burning Empire - have backstory as part of character generation when creating skills and other stat lines. So even if your player didn't make a backstory, you can probably grab some elements of one here.
Advantages and Disadvantages
My general view is that advantages and disadvantages are the player telling you not just where they are willing to spend points to have boons and where they want to get points for weaknesses, but where they want to be challenged and what they want to use to overcome those challenges.
For example, if a player puts down a trait like Dangerous Beauty on their character sheet - even if they don't play into it - they want the fact that their character is incredibly physically appealing to play into their adventures. Not all the time, but every now and then it should come up and play in their favor. At the same time, if a player has a disadvantage where they're known as being something of a loose cannon, they want that fact to hinder their progress or prove an obstacle to be overcome.
As the GM it is your job to bring these up. The character's natural tendency will be to emphasize strength and mitigate weakness. A good player will play into their own faults. However, you should still work to bring it up. After all, a player can point out they have a bad reputation, or act into the greedy/lustful ways, but only the GM can make the world play into that.
One of the best places to get ideas for a character's personal plot is the player themselves. Players will often have ideas for challenges and obstacles they want to face, or for adventures they want to have happen They don't need to know the whole plot, but you can talk to them for ideas and whatnot that you'd like to play out. Maybe you want to do a story for the thief in your group where they're old guild comes looking for them about some old job. Asking the players if that's part of their history they'd be interested in seeing more of can not only get you approval before putting the player in an awkward spot, but also get ideas from the player about people that might be there or other ties that could come up.
Use the player to generate ideas, design structures, or even to gives a headsup on certain - not core plot elements - that will come up. If the story is about them and their past, it only makes sense that they'd have more information than the other PCs about it after all, right?
The Other Players
What about the other players? After all, you can't just dedicate a session to one player of a group and have that be ok for the other people. We're going to talk about this on Wednesday. Sorry if that makes the opener feel like a bait and switch, but this post went on a little too long as is. See you Wednesday.