plisnithus8
Adventurer
A "henchman" might be a better description. Squires were usually the sons of nobles, there to learn, rather than placed on the frontlines. You don't want to endanger the life of a noble if his father can squash you like a bug.
"In time of war Medieval Squires accompanied Knights on the battlefield, leading and tending the horses and dressing them in the Medieval Knights Armor. They came under fire from arrows and many Medieval Squires were killed doing their duty."
I think war-time could be a hook for a campaign as could other reasons a squire could accompany an adventure such as a very minor noble wanting his son/daughter to earn the fame and riches that local adventures have acquired.
http://m.medieval-life-and-times.info/medieval-knights/medieval-squires.htm