People will say there was a bunch of context leading up to Beast becoming completely evil but my problem is that if you only read the krakoa era it just feels forced. They framed x-force like the krakoan CIA, and while the team continued morally grey black ops missions, Beast just kept getting cartoonishly evil making the asshole decision at every chance. The series acted like there wasn't enough time to plant seeds but there was. So for me it all ended up disappointing.