The relationship between KeyWorker and young person is not ordinary, even though the KeyWorker may make use of much 'ordinariness' in his or her interactions to develop and maintain Engagement. The entire focus of the KeyWorker is to use this relationship as a platform to facilitate meaningful change for the young person. Every interaction between young person and KeyWorker is dictated by the Boundaries of this relationship (Patient-Worker Boundaries).
The KeyWorker uses an understanding of the nature of an Attachment Relationship to help foster the most therapeutic alliance possible, a process that is documented under Engagement - the aim is to build a strong therapeutic alliance.
A key element in the formation of good Engagement is the creation of Epistemic Trust, and in turn, this is built through good Mentalization by the worker.
There is plenty of strong evidence to support the importance of the therapeutic relationship, (or Treatment Alliance) as being an extremely important part of what connects to improved outcomes.