I always thought of Bellatrix as a feeling type because of loyal and devoted she was to Voldemort. Also in the books, she seemed like almost an introvert.Narcissa is an ISFJ.
Bellatrix in the books is ESTJ ,in the movies they somehow make her seem ESFP.
Bellatrix is definitely an extrovert and a Te user, I don't remember her using Fe at all.
I'm not sure that is the case for all ISFJs. I mean, yes, I agree on a personal level (I even feel bad killing bugs) but ... there were ISFJ Nazi commanders who oversaw the slaughter of hundreds of thousands. Pair a fanatic with racism and a Fe-user can justify anything (Hitler, also, was an IXFJ type). Bellatrix was insane...An ISFJ would find it impossible to murder somebody. I have trouble speaking up and getting into a debate with people; taking somebody's life is completely unthinkable to me 0_o