Obviously, if you are on this site at all, you probably read the story.  So you know how the Marauders got into the Order - how James and Sirius went for job interviews to be Aurors for the Ministry, and how James walked out in a huff after learning the Aurors use Unforgiveables.

This in turn prompted him to find something else - he didn't want to give up his chosen career path just because the Ministry goes against his beliefs.  So this is when he approaches Dumbledore about the Order.

I really enjoyed this little brainwave I had.  Out of all the Marauder fics that I have read that even SHOW them joining the Order, they usually join because of one of two different things:

1.  Dumbledore asks them to join because they are talented.

2.  Somebody (usually James's parents, it seems) is killed, prompting fury and a desire for revenge.

I have actually had people tell me that the way they got into the Order in my story was surprising to them, and different.  (I'm unsure if this is in a current review or in one that was lost in the server crash in 2008).  This, in turn, surprises ME.  I think the way I have written it makes perfect sense, and not only that, it is canon that Barty was head and that he allowed use of the curses.

I can think of arguments to both reasons I usually see for the Marauder's joining.

1.  Why on earth would Dumbledore ask children to risk their lives and join his Order?  I don't think he would do such a thing, no matter how talented they are.  To take it one step further, why would he ask them to drop everything, their futures and any possible careers?  They are fresh out of school, they've got everything ahead of them.  Why would Dumbledore take that away?  And how could he ever ask any of them but James or Sirius to do such a thing, as those two are probably the only two well enough off to support themselves without a real job?  Of course they could always get side jobs, but Dumbledore couldn't count on that, and I just don't think he would do such a thing.

2.  This one is a little more believable for me, but it doesn't really go with canon.  James's parents didn't die to any Death Eater attack;  they died to illness.  Of course, it could be somebody else's loved one that is killed.  But as far as characterisation goes, I don't see anybody but James as going so actively for revenge, and getting all his friends in on it, too.

But I can't think of anything wrong with my own idea, especially when the use of Curses is a canon fact, and if James is anything like his son, I don't think he could work for a Ministry that does the same thing as the enemy.

Perhaps James's knowledge of the Order could use a little work, however.  In my story, James knows the Order exists because he overheard Dumbledore and his father talking about it one summer.  He keeps it a secret, but remembers it when his dream of being an Auror doesn't work out, and he approaches Dumbledore (along with his friends) of his own decision.  I'm not sure if I like the way he found out the Order exists... but I do rather like the way he decided to be a part of it.