A PhD student has been working with Prof A. However, after a year, the student decided that he doesn't like the field and wants to change his advisor to Prof B, who works in the same department with Prof A.
Would there be any potential adverse effects on relationships if the student changes PhD advisor from Prof A to Prof B within same department, especially when the student has strong previous connections with Prof B?
Can Prof A advise Prof B not to take the student in such a case? Has anybody experienced cases like these and what the results were?
Assume Prof A is tenured and Prof B is not .and Prof A was against co advising from beginning.