A person that feeds off of the life force energy of another person is known as an Energy Vampire. These relationships are parasitic.
Energy Vampires are known to feed off of negative attention, cause unnecessary problems, pick fights, are deceptive, flip out when least expected, are notorious guilt-trippers, master manipulators, and are prone to making threats.
For the most part, Psychic Vampires are not evil or ill intentioned. They are victims of their own minds. They feel helpless, powerless, paranoid, strive for unattainable perfection, self-medicate, engage in extreme behaviors, and/or are preoccupied with being right.
Psychic Vampires do not know that they create their own reality. They have a lack mentality - their focus is on what they don't have. They do not feel it is possible to get the love that they desire. They do not trust themselves to fulfill their own needs. Consequently, they believe the only way to get what they need is to take it from others.
Indigos and Empaths are innate healers and are drawn to those in need.
Newsflash: Energy Vampires don't want to be healed!! They don't want to be saved.
It's the attention you give them when they have a (self-created & unnecessary) problem that they crave.
They are survivalists. As long as they have a food source - you, they have no incentive to heal or take care of themselves. The more you try to solve their problems the more problems they are going to have.
You open the door to Energy Vampires through your insecurities. You may have your own feelings of victim-hood or powerlessness. You may be approval seeking. Co-dependence issues is their golden ticket to ride.
It's possible that you may only feel good about yourself when you help others. You may feel unworthy of love or friendship unless you do something for it. You may feel guilt for having good fortune when so many others seem to be down and out.
You may have an addiction to Energy Vampires. Do you like being needed? Do you have the need to please? Does being around an Energy Vampire make you feel better about yourself?
You may be an Energy Vampire yourself. When you allow yourself to be drained by an Energy Vampire do you turn around and drain somebody else? Do you only get attention when something negative is going on?
The truth is, you have to vibrate on the same level as an Energy Vampire in order to attract one into your life. Your thoughts and your core beliefs are what creates your vibration. Your emotions are your indication as to what vibration you hold.
No protection technique is going to save you from an Energy Vampire.
Commit to doing what it takes to be happy. Raise your vibration so high as to not be a tool for an Energy Vampire. Don't live your life based on others expectations of you. Meet your own needs. Set boundaries. Saying NO does not make you an asshole (though they will certainly try to make you feel that way). Being a good person is not determined by how much you self-sacrifice.
Be a vibrational match to the kind of people you want to be around. If you want to be around respectful, competent, and well adjusted people - you need to project those qualities from within yourself. Root out any negative core beliefs about yourself that attract the people you don't want in your life. Transmute those beliefs into positive ones so that positive people will show up accordingly.
Realize that Source is an infinite energy. We all have our very own stream of Source Energy. So, it is actually impossible to give away your energy or to have it taken from you. It's just that Energy Vampire's actions cause you to have negative thoughts that pinch you off from your own Source. When your Source Energy flow is restricted you start to get physical symptoms of exhaustion, confusion, depressed, etc.
Make feeling good a priority. Get your Source Energy pumping by doing what you love and what energizes you. Love yourself enough not to be liked by those that exhaust and bring you down. You don't owe anyone anything. You are worthy of a reciprocal and respectful relationship without having to serve and provide your life force energy.
You can hold thoughts that allow Source Energy or thoughts that resist and restrict it. It's up to you. Consider doing Shadow Work to uncover your resistant vibrations.