The aberration hunters are a division of the Vanguard dedicated to the extermination of aberrations. Due to the danger that aberrations pose of becoming larger threats if they are not dealt with quickly, the division boasts some of the strongest members of the Vanguard. This means that in order for aberrations to become more powerful they must be fed in secret or well behind Abolish lines where they can be kept safe.
Before the Rainlords became enemies of the Vanguard, Cisco and Dennex wanted to join the aberration hunters, due to their shared belief that the way that aberrations preyed on the helpless was disgusting and that they were abominations to be destroyed at almost any cost. While he would have been allowed to request a transfer as the servant age of four, he expected to be refused until he was older and more experienced.