I'm curious... there are quite a few builds that suggest adding Paladin to the character. Where I have no problem with that, my only concern is doing something that may cause the character to become an Oathbreaker. In general will that "ruin" the intended build? Or are most build suggestions more adding it for the base proficiencies? Does Oathbreaker deviate from say just a Vengeance build that much?

Also, if my main character does something "questionable" does that cause my companion with the Paladin build break their oath by association with you?