I understand being part of the chaos family means your crazy, but what happens to the marine if he really goes off the deep end and can no longer control what he does? Now this is with no demon help or gods push. I am talking about the marine just can't take it any more be it he lived to long or has seen so much in his life that he snaps. What would other chaos space Marines do with him? would they just shoot him or leave have him on some back water planet to run crazy on the things that live there? Would they put him in a dreadnought or what? please give smart answers to this topic.
In the Horus Heresy books you can see Space Marines Insane in the World Eaters, that capitol in the battle become kill machine and after they don't remember anything. Other example are Wulfens in the Space Wolves, in that case, the space wolves can become in a beast like werewolf and when that happens the others space wolves kill them.
are u sure about the killing part?! i thought that sw dont have a lot of problems with wolfen considering that 1 of their wolflord is 1 and he has like a full company of them http://wh40k.lexicanum.com/wiki/Bran_Redmaw#.UvzCks74TAU
Also keep in mind a space marine is the product of extensive hypnotherapy and indoctrination, some people consider modern people jaded and desensitised to many stimuli such as blood and violence or nudity and sexual references in modern media...a space marine has been for all intents and purposes brainwashed and programmed to fulfill his role in the legion be it loyalist or chaos. The ones that do lose their sanity in a loyalist legion would as Grigdusher suggested be cycled into an appropriate position in a "death squad" type unit but only after all attempts at rehabilitation/recovery via further hypnotherapy and indocrination had failed. As for an insane chaos marine...lol...assuming his brothers could tell the difference or even care if they did notice, I'd imagine the common decision would be strong chains and a leash and reassignment to a "death squad".
All Space marines are insane. I believe it's due to a lack of sex... They hang around a bunch of guys all the time...no women!!
Most Astartes deemed irrevocably insane are sent off to kill as many enemies of man as possible before eventually dying. Can't just have the geneseed and organs sitting in a body locked up somewhere, so they send them off to die gloriously and harvest the organs. As for Chaos, any insane marine who can't tell friend from foe is usually abandoned or surrounds himself with other like-minded individuals. Contrary to popular belief, the Chaos legions wouldn't be as effective if they were all mindless bloodthirsty killers who don't bother themselves with friend or foe. The crazy ones are either abandoned or sent off on, again, suicide missions to bring as much chaos and destruction as possible. Think Warp Talons or Khornate Berzerkers. They don't normally function inside a mixed warband, and operate under their own leadership.
Well, the 13 company is a good example of that you say, they are astartes and wulfen but thats wulftartes can get the control about themselves for the labor of Wolf Socerders, they a can relax wulftartes and they don't lose his mind. But exist others wulfens, when a initiated in the space wolves drink the wulfen calyx the initiated has to take the control of himself because he shouldn't take the control he become in wulfen and this wulfens has to be hunted because this wulfen can take the control again. So, it's right all of the wulfen aren't killed, only wulfen uncontrolled are killed. Sorry for my bad english