Do well by somebody
Definition 1 of 2
Pro Tip 1/3Positive Action
Implies positive intentions and actions towards someone's welfare or benefit. 
He always made an effort to do well by his employees.
Pro Tip 2/3Moral Responsibility
Carries a sense of moral obligation or dedication to supporting someone. 
As a mentor, I feel it's my role to do well by my protégés.
Pro Tip 3/3Mutual Respect
Often used to show mutual respect and trust in personal or professional relationships. 
She's a loyal friend; she'll do well by you no matter what.