Worst treated companion in your "canon" run?

For me it was Jaheira. She was with my party as soon as I was able to recruit her. But...

I helped kidnap Isobel, therefore getting all her harpers killed (which I then brutally beat their corpses, so really I double killed them).

I then lied to her about it all so she would join me. And she was a great team member, really pulled her weight.

I got her guild friend, Nine-Fingers, killed.

(I saved Minsc)

I ransacked her hideout, including incredibly sentimental items which I then just threw in my travelers chest of stuff.

I stole the control of the Netherbrain for myself and then subjugated her to make Baldur's Gate in my image.

Side note: Just finished the game - 177 hours on tactical (what a fucking game!)