How do you imagine - B lies between A and C, going from A to C passes through B. What else is
there to say?
Well actually there is quite a lot to say about Miller effect, stored charge in saturation, these are covered
in many texts on BJT's.
I guess the most likely issue you will encounter is the delay before turn-off and slow turn-off due
to stored charge in the base region during saturation - for fast logic using BJTs (ie the old TTL families)
it was common to add schottky clamp diodes between base and collector to prevent full saturation and
thus prevent stored charge build up.
Stored charge in the base takes a while to clear once the base lead current stops, a common technique
to speed up switch-off is to reverse-drive the base to speed switch off (but not too much, as its very
easy to completely destroy a BJT with more than a couple of volts reverse bias on the base-emitter junction)
Stored charge effects are most noticable in darlingtons, turn off delays of many µs or tens of µs are common.
Its the reason silicon phototransistors are much slower than silicon photodiodes too (as used in
many optocouplers), and why darlington motor drivers like L298 cannot handle high PWM frequencies...