If its a freindly under a charm spell then its unfriendly. Its attacking me and i have no control over it. Therefore, for the duration of the spell it should be red circled - which would clearly show the change in disposition.
If i want to attack it or not - is my choice, so leaving it to be greencircled and requiring me to use ctr+attack combo is pointless waste of time. I can attack it or decide not to while its red circled all the same.
Point being, i report - for devs to take a look and decide.
*shrugs* I kinda think the green outline, floating hearts, and "Charmed" status which shows on the side-portraits and mouse-over do a good job showing the change in disposition.
It is possible to save against Charm (and I should check to see if you can Charm them back onto your side). Maybe killing a charmed summon is the best action, but if it's a charmed party member, attacking them is not going to be of any use to you, unless taking damage snaps them out of it. Does it? Hmmm.
Yeah, it is for the devs to decide. That doesn't mean that I can't offer my own opinion.