I hate to say it, but RT would be a better game if the heretic path just didn't exist. It makes no sense. Everyone would just kill you. You cannot walk into a dynasty and start doing overtly chaotic things and expect people to just go along with it. Jimmy, Ulfar, Argenta would literally just shoot you in the back of the head. You would be dead the first week.

Adn even the others besides them would stop you too. Cassia is not a heretic, she loves the Emperor, so you'd just get eye blasted one day when you said some heretical shit that went too far. Kibbelah going along with a heretic domin is also pretty questionable since she's incredibly devout in service of the Emperor and chaotic shit explicitly acts against the Emperor and humanity, but they handwave it by saying she's just soooooo susceptible to your influence that she gets corrupted. It's stupid. If it was more realistic, what actually would happen is she would slice your head off the second you overtly went against the Undying One.

Jae is also not really that much of a heretic. Sure she breaks the law and dabbles in illegal ways to make money, but there are actually several instances where she reveals that she's not that bad of a person, and her sins are just making money, not actually hurting the Imperium or defying the Emperor on purpose. She would not stick around with someone who is overtly heretical. She likes bending the rules to make some money, but she doesn't partake in the actual bad kind of heresy.

The entire heretic path in the game is unrealistic, requires tons and tons of handwaving, requires the people around you to act illogically, and is just one big long nonsensical farce that constantly stresses your suspension of disbelief. Sure, Argenta and Jimmy and a few others eventually leave, but it's genuinely absurd they wait as long as they do, and it's absurd they don't actually do anything to you. It's nice that there is a secret heretic companion, but it doesn't make up for the whole thing.