Roan looked through the missions on the board to find a good target. After all, he didn't want to get expelled so that he could keep an eye on the mission board. If someone posted a reward on his or Rean's head, he would know beforehand. That was the main reason he joined the Shadow Reapers.
The second reason was that he could find some good practicing targets. Assassinations were different than head-on combats. They were silent and usually required some planning depending on the target. Rean and Roan's skills were just perfect for both movement in the shadows and hiding from Spiritual Senses.
