Board Thread:General Discussion/@comment-10317392-20130906010815/@comment-16774229-20130906155224

Here's my idea on why Roman is stealing Dust:

In exchange for Crimson's services (assuming she's a Grimm cultist, or somehow under the influence of Grimm), he has to go on assignments for her. The Grimm want Dust, and human Dust users under their control, because that's how they were defeated last time. They also want him to get rid of Beacon so they won’t need to deal with Huntsmen and Huntresses.