I'm re-reading this part with the whole elopement, and the thought came to mind about whether or not we really know why Wickham ran off with Lydia. I know that he had no intentions of marrying her in the slightest, so it comes down to why he would take her along on his trip to London. I had always been inclined to believe that he wanted to get revenge on Darcy and, seeing that he liked Elizabeth, decided to run off with Lydia to ruin his chances, but the more I read into it the less I believe that to be so - in my opinion, I really couldn't get out of the earlier scenes that Elizabeth had given Wickham any real hint about her newfound lack of hatred, or that he would have known Darcy's feeling for Elizabeth.

So that leaves me with the idea that it was an accident, that he needed the money to get away from there so he used Lydia, or accidentally ran into her that night and she begged to come alon, but I still can't believe that anyone would be desperate enough for money that they would bring Lydia along with them (she's not my favorite). Yet there was the rumor of their partiality.....

So, now that I've confused myself, back to the real question - Do we ever really know why Wickham ran off with Lydia?