As I said in your other thread;
"It's not a flat -1 modifier.
But yes, charisma is acting very weird. Low levels only remove bonusses of opponents, not add to your own roll, and only 4+ add to your own roll... that's what my own tests showed anyway."
You'll notice the modifiers of your choice because it's listed under 'modifier' (NOT charisma bonus). Seems 1 charisma just undoes enemy penalty, and early on most NPC's don't have that... I'm not sure if your teammate will ever get that 0_o
