|The following is based on pre-release information for the canceled online game codenamed Project V13 and is not considered canon.|
This is a High Calling, Brother. I'm sure you will do well.”— Elder Francis
Miller was a Brotherhood of Steel scribe set training missions with the Guardian Brotherhood for the purpose of combat training. The missions, assigned by Elder Francis, had the primary goal of finding out if there truly is a tunnel entrance to the Glow, and also aimed to keep the Brotherhood connected with the outside.
Miller, as a scribe, was more comfortable conducting research in the safety of the base, and as such not nearly as confident in combat, he was slightly overwhelmed by it all, something he could sense some of the team knew. In fact Francis had assigned Miller this mission in particular for his scientific mind in the case that, should the information of a tunnel entrance prove factual, any obstacles could be assessed and understood. Miller served his squad as best he could, but was quick to come under sarcastic snipes over his abilities, particularly from Jenkins who used the tensions to pressure Miller into giving him his hardened power armor.
Jenkins was later knocked down during a scout-ahead and Miller pulled Jenkins to safety where he was able to accurately assess a creature previously unknown to the Brotherhood, a mutant mantis shrimp.