This achievement can't be missed and will come from natural story progression.
To be honest there is no necessity for a guide on how to get this achievement. Since you cannot fail it. However there seem to be quite a few problems with the achievement unlocking system of this game and the Xbox one in general. So I thought it could be useful to have a little reminder when this achievement should unlock so you know that nothing glitched for you.
I will mention the actions you have to participate in right before you get your achievement below.
*** Spoiler - click to reveal ***While playing as Rodrick, you will have a conspiratorial meeting with Gwyn of house Whitehill. The achievement will unlock after you have talked to her.
Just in case you need further information about the situation described above you can refer to the video below (video credit goes to: VGFAQ)
Hope this helps you guys ;-)
Any improvements? Let me know in the comments!