Spotter

"Guillimans Codex instructs that as neophytes we are trained in infiltration and sniping; why then, when we don power armour, do we forget these tactics?"
Memtes Machus to his sergeant at the seige of Gollon Hive, M.41

Name: Memtes Machus
Chapter: Heralds of Sigismund
Company: Phi (Reserve) 
Rank: Sergeant (Tactical Recon Squad)

If you’ve ever fought space marines and lived, you might find it a curious sight to see a tactical squad stalking across embattled streets without a sergeant; that is, if you see them before a sniper shell exits the back of your head. Indeed, some amongst the Heralds find Memtes’ tactic of commanding his squad from atop high places damaging to his squads morale, but the truth is his squad have never withdrawn or needed support knowing their eagle-eyed sergeant is diligently covering them. He is a calm hunter, and a compassionate leader, who has refused entry to Beta Company’s sternguard several times, worried for his squad’s safety away from his watch. 

Rather than use a las variant of rifle, Memtes carries a heavier but more powerful modified boltgun, similar to the patterns once employed by the Legions Astartes. His armour is covered in kill honours and star charts depicting campaigns and stories of his deeds, although you’d probably have to have also been raised in the northern stargazer hives of Occultus Prime to decipher their meanings. Some worry he his vulnerable in tall towers without his squad protection; others simply worry he gets lonely; neither of these are valid concerns.