Well, it's not standard here obviously, but as long as standard RP requirements (profiles, plot, etc.) are followed, I have nothing against you starting a one-on-one RP. Speaking of my experience of such things, however, I do feel inclined to point out that those tend to die quickly unless both RPers are really 100% devoted to the cause, so if your plot can be altered to include more people, it may increase the lifespan of the RP. As long as it's a working plot, I have no objections either way, though. However, please do add a disclaimer in that case so people won't waste their time signing up for something they can't get into.