I was about to make a post about this, but since this is here, i think i will say it here.
Usually you achieve the renegade route by being an asshole to your "friends", which to some people seems a bit forced or even wrong within a human standpoint.
But id like to propose a reason or interpretaion of the story to why this would make sense storywise.
Of course you can be nice and do the stuff to get all the 100 Bad Karma Points but then you enter the renegade and theres a big shift in character, so it makes more sense to be somewhat a "bad person" through your playthrough.
This is how i did my renegade route:
At the beggining your mother disappeared (since we dont really know what happened), so you are in a new place, basically alone and with a somewhat traumatic event. So here i usually choose neutral / slighly good options, since you are not really a bad person, but you are not overly friendly either.
This continues through all the chapters. Even the Marianette stuff which in my opinion is the worst to make "bad choices" (it feels really bad). Because yes, you are trapped in another dimension or whatever, but its not really her fault, and she even helps you so i see no reason to be mean to her. so again, neutral / slightly good options.
Now the pivotal moment is the blacksteeple castle stuff.
So picture this:
Sorry if you guys had to read everything ahah. This is just my interpretation.