<Snipped quote by TheDuncanMorgan>
This is a question which needs to be answered with sophistication. I haven't yet figured out the best way to do it, but I can at least name two possible scenarios.
1)Collaborative posting: What you could do, and what I might recommend, is working closely with the other RPer on a post in which your characters interact. Generally this would be done on an online document (google docs, or titan pad, or PM), with each writer adding their own bits and pieces in succession in order to etch out realistic dialogue. I like this method, but I find it can sometimes hamstring certain writers by focusing them on the moment, and the dialogue, rather than the larger picture. The most important aspect of this method is that the writings are combined at the end and posted as one, under both names.
2)Successive posting: In this situation, you and the other RPer would communicate strictly of the dialogue and work out what the conversation is going to look like, but making your own individual post. This could lead to inconsistencies, but it leaves your authorial intent untouched and your message clear. This method implies the duo coordinate the release of their posts until both are happy.
Sorry for my incompetence but could you explain number 2 again?