Whilst a character might well stay with a unit for the entire course of a battle, there often comes a time when they depart for pastures new. This might be because you need your character to take charge of another section of the battlefront, or because the character's current unit has been so mercilessly butchered by the enemy that they are no longer safe within it. Whatever the reason, we're going to need rules to allow a character to leave a unit.
A character can charge out of a unit, by declaring a charge in the relevant phase – in which case, they will move and their unit will stay still – it is not permitted to declare a charge of its own, though it can move during the Remaining Moves phase. If a unit contains multiple characters, only one of them may charge out of the unit per turn.
If a Stand and Shoot reaction is declared against a character charging out of a unit, the shots are fired at the character as if they were a separate target – they do not gain the same protection as being inside a unit, but they does get a 4+ "Look Out, Sir!" if the unit they are leaving is the same troop type as they are.
Alternatively, any character can leave their unit during the Remaining Moves sub-phase by moving away from the unit before that unit makes its own move. If the unit cannot move in this phase for any reason, the character may not leave the unit. A character may not leave a unit on the same turn that they join it.
For example, a character cannot leave if:
Their unit is fleeing.
The character themself or their unit is not permitted to move by a spell or other effect.
If the unit is in combat.
If the unit has made a failed charge.
And so on...
When leaving a unit, the character reverts to their normal rules for movement. The distance of their move is worked out from their actual position in the unit before the unit moves. they can even join another unit as part of the same move if their controlling player wishes, and the character has enough movement, although the unit they join cannot move if it hasn't done so already.