EHy guys,i encountered this problem,well it seems the companions won't give me the quest to purify them,i have the 4 heads in my inventory,yet they don't seem to say anything.Any tips?I'm half the storyline,need to do a cornered rat,if this may help.(Perhaps they won't trigger 'cause i got too far in story)

They do not do it straight away, you have to wait a bit so go do some other things and ask later. And then save before asking in case you asked the wrong brother and some strange glitch occurs. I never had that problem, just pestered them till one eventually said he would.

Go for Farkas first. If you get it from Vilkas first there's a glitch that cause him to stop following you to Ysgramor. If you do the quest for Farkas first, then go straight to Vilkas, you should be fine. Just do as stated above, keep on asking them for jobs, and always save before you talk to them.