Hey. I am also a therapist and I have had something very similar happen to me, only the client hadn't actually worked with the other therapist yet. The client was set up for an intake with another therapist. That therapist was then going to take on his case. I ended up having to do the intake, but I was supposed to still turn the case over to my colleague. The client and I ended up connecting quite well during the intake, and he asked if he could work with me instead. I spoke with my supervisor, who said this was absolutely fine.

Your colleague should really have no influence on who you take on as a client. However, it is important to discuss this with your supervisor. There is more to it than just switching therapists. The client should have a termination session with the current therapist/intern. Also, feelings should be explored as to why this person wants to switch. Ultimately, the client should be with the therapist who will be most beneficial to his/her treatment-- if the two of you connect welll, then perhaps you should work together... but it is important to consider all factors. Again, I would never take direction like that from a colleague. I would also not go through with a switching of clients without making my supervisor aware, as well as the intern, and then discussing the implications, thoughts, and feelings surrounding the situation.