I am starting a campaign with a group that tends to have lots of backstory and I am not really very good at coming up with a good one.  I can usually flesh something out over time, but I would at least like to start with something.  I would appreciate any suggestion son where to go with what I have currently. 

The character is a high elf rouge and I will be taking the arcane trickster subclass at third level.  So many people use the dead parents/tragedy back ground and I thought it would be good to go with the opposite and have loving parents who are wealthy, but just want me to be a part of high society, not an adventurer. I was thinking that I could have gone to school for wizardry, but dropped out maybe.  My character also has an irresistible urge to steal stuff.  He pretty much will take anything as long as it is not his and his goal in life is to be the best thief ever.

I know I have some decent things to start with, but I can't seem to come up with a way to tie them together.

I mean, it sounds like you've gotten most of it. Use your background and the traits generated from it to guide you. If you're not sure, try rolling for the traits and making a story to explain why your character ended up that way. Don't feel you need to have everything solidified - some of your character doesn't drop into place until you play them for awhile. For example, if you end up with a flaw along the lines of "I abuse substances" or "I enjoy carnal pleasures", maybe you started stealing to fund your proclivities without having to explain them to your parents.

Personally, I would avoid the kleptomania angle, because it takes choices out of your hands. I usually think it's more interesting to have traits determined by experience ("I steal because I need to support my drinking without my parents knowing") than a nebulous mental illness ("I steal because I have urges to"). But obviously you should go with what makes sense and sounds fun to you.

Thanks for the advice. Your point about the klepto mania is good. After thinking about it more I think he would be more absent minded. He would put something in his pocket without realizing it, like a lighter thieft 

Quote from Wikedeye >>

Thanks for the advice. Your point about the klepto mania is good. After thinking about it more I think he would be more absent minded. He would put something in his pocket without realizing it, like a lighter thieft 

Pretty much, except I would not have a problem being called a thief. 

I'm also running an AT in a side campaign and wanted a fun back story. My rogue is young, arrogant and thinks he's destined for greatness. He's a skilled thief and feels like he has a lot of magic potential, so he's obviously better than all those normal thieves. He wanted to prove how good he was, so he stole something valuable from someone powerful in town, but got caught in the process. So now he's forced to run and find work in some other town. He was planning on leaving anyway because they were holding him back from his destiny. There might even be some bounty hunters after him. That's up to the DM.

That's what I came up with for mine. Feel free to use it and tweek it for your character. 

Here is my rogue concept.

My rogue grew in a moderate household to a banker inside a port town known Black Water. He quickly realized that he was bored with a normal life and through the introduction of a childhood friend he met a small thieves guild known as Black Light, there he worked happily for five years and he gained a big fortune from stealing and selling objects he looted from houses and passing ships. Then it all ended when a thieves guild known as the Knicks belonging to the town next to them began to move into Black Water. A war began where my rogue lost his pinkie toe, not long after that all his friends and comrades were either captured and tortured or killed on the spot. And my rogue as the only one left was filled with rage. Not because of the fact that all his friends and guildsmates are dead or captured, neither by the fact that his guild was now disbanded and he would have to move to another town. He was mad because in the midst of the war four members of the knicks broke into his home and tried to steal from his hoard. He was able to kill three of them but the last one escaped along with five copper coins. The coins stolen sparked a unstoppable bloodthirst where he now has one purpose in life, to kill all the knicks in the world. In the spur of the moment he chose to do something that would begin his path to infamy. He chopped of the index fingers off his victims corpses and threw them into the ocean. Thus he gained the nickname that caused fear to even the most bravest of hearts. He was now Fingers.