Sherry is a mouse that can join your party as a character.
To find her, enter the kitchen in Lord British's castle in the
east wing. Get the cheese, then enter the east wing room with
the potions and crystal ball. Locate the mouse, and talk to it.
Say "SHERRY" and she will ask for cheese. Answer "Y",
then "Y" again. Say "JOIN" and she will become
part of your party. She can be used to collect items that are
unreachable by the other members of your party due to her small
size (for example, the Rune of Valor).
Strategy
Strategy: Cheat mode items