If the shadow and the caster are unable to communicate, then it will simply defend the caster and those that are working with them.

Ally (Typical Shadow, 100% of point total, Appears Automatically) [54] 
    Summonable [+100%] 
        Summons a different shadow each time 
    Cosmic (Requires no reaction roll) [+50%] 
        The spell makes them friendly to the caster 
    Extended Duration (x30) [+60%] 
    Magical [-10%] 
    Spell Components [-30%] 
        Must say "shadow" in Latin 
        Must gesture with hands 
        Must hold a bit of smoked quartz ($0.20) 

• Typical Shadow.gcs