What is this effect I am seeing in a current/voltage plot of a 2N2222 NPN transistor?
That is what is expected even with the simplest model of a BJT. You can see it in this simulation

If we zoom in in the VI chars

we can see that the chars do not intersect at 0,0

The shape of the curve (excluding the Early bending) can be seen in these equations (Millman Halkias, Electronic Devices and Circuits,&quot;Voltages as functions of currents&quot;, p. 250)

which lead to

or, in more modern notation

This is the plot of Ic/Ib vs Vce with Vth = 26 mV, alpha = 0.99, alphaR = 0.78. It's rotated by 90 degrees because we are plotting the inverse relationship

and if we zoom in near the origin we see

that is compatible with what Millman shows in his textbook

Note that the 6 mV values is Vth log (1/alpha_R).