Suzie is a neighbour of Mitchell, George and Annie. She is invited to their house by Mitchell, as Mitchell wants to live a normal human life which includes contact to the neighbours. She is a friend of Hannah and lives in number eight. When Hannah leaves the house she is already gone since a long time.
Suzie is also one of the neighbours who were infront of Annie's house when Bernie died. She didn't say anything and didn't accuse Mitchell directly, but she watched the scene where Jim is shouting at Mitchell. When Bernie gets infront of the car she screams.