On Aurelia and her SO
Erebus... and to a lesser extent kor phaeron present a very large obstacle for her SO to overcome. And the simple fact of the matter is that if the SO doesn't allign with chaos. Erebus is going to try and kill him. and so probobly will kor phaeron. Which means that their is no way all three of these charecters are making it to the horus heresy. which means that either the SO doesn't make it or the horus heresy may very well just not happen.