If Quinn Heinest was a two-faced girl who liked to manipulate people around her with her sweet demeanor, then Andrew Heinest was a wise man that honored friendship and loyalty. Nevertheless, he had one weakness: his overwhelming guilt toward his sister, even though he did nothing wrong.
Whenever Quinn asked him a favor, he would grant it blindly before seeking the truth behind her wish, thanks to his guilt feeling. However, if he witnessed his sister's misdeed or heard complaints from others, Andrew would scold Quinn and make her responsible for what she did. Aside from that, he would listen to his sister's wishes and believe everything she said.
Even now, Quinn tried to control her brother by taking advantage of Andrew's guilty feeling for her. She was thrilled as Andrew believed her words and deemed Richard an enemy.