Who is Suzie from About a Boy and what is their importance?

Suzie is Fiona's childhood friend and a member of SPAT. Suzie meets Will at a SPAT meeting and takes him on a SPAT picnic. It is at the picnic that Will meets Marcus and finds him to be something of a surly child. Suzie is a minor character, but she is important because she is the method through which Will and Marcus .