Glad you enjoy it! In the Apprentice route you make Father Martín your Master, which means you submit to his ways and teachings and rule the Convent under his demonic influence.
Despite, if you're interested in a real submissive playthrough you can trigger those routes by choosing any of these options ;)
Once you start Day 5 you can either choose to resist and try to remain pure, or give in to temptation and become a slave ;)