The title is completely misused.
Stockholm Syndrom is an emotional response, that happens to some abuse and hostage victims(as f.exp. The Uke) - they end up having positive feelings towards an abuser or captor - loving them unconditionally, making it hard for them to see reality.
In this story (till now) it's just hatred on hatred; a captive with PTSD.
It's okay but I really hope it'll be able to develop into the real case of ShSy.