A user who is considered to be Riven is past the point of The Fallen and it just one below Ivich Supporter. These people have surpassed all kinds of hell in the downward spiral of the entire User Spectrum. Once somebody reaches Riven and beyond, there is a very small chance of getting them back, usually not at all.
Rivens act and seem almost emotionless. Their head conflicts between leaving or joining the only places above them being Ivich related of any sorts. Since there is such a huge gray area between Venkon and Ivich, there are many outcomes. The closer it is to Ivich, the more likely they'll join Ivichs. The people in Riven mindset will most likely end up on the Ivichs side than dropping out of the war totally.