HP

HP stands for Hit Points. When this number hits 0, the unit will die. If a player unit dies, they will be inflicted a Grave Wound, and will be unusable for the rest of the chapter.
When leveling up, Aptitudes work the same, but when getting a stat increase, HP goes up by 2 instead of 1. Instead of getting 0 HP when missing the stat increase, HP will be increased by 1 every time a unit levels up.