True Stalker was a Sphinxian treecat who had bonded with Arvin Erhardt. He was known simply as the Stray to other humans. After Erhardt was murdered (his aircar was sabotaged, in an effort to make his death appear accidental), True Stalker trekked a huge distance across Sphinx in an attempt to find help to avenge his murdered companion. This was extraordinary since the despair and grief involved in losing a human companion almost always caused a treecat to suicide or starve to death.