Grex Ay (A) is in some sense "first among equals". They speak Latin as a cant and rarely recruit trainees; prefering to either recruit from the other greges or out of work soldiers from other walks of life. Their unit badge is an upwards pointing arrowhead.
The Grex is no-longer double strength since 1218 and some of them are Time-lost Roman Legionaries of the 9th Legion who arrived in 1210 from 120AD with Gaius.