A manipulator is a person who gets other people to do what they want by using guilt and sneaky, underhanded tactics. All the while they somehow manage to come away looking completely innocent. Life can be very stressful if you have to interact with people like this, especially if they are family members. Hopefully this information will bring light to your situation and help you better deal with the manipulator in your life.
Try not to be around a manipulator in the first place. Manipulators rarely change, so the best thing you can do is get away and stay as far away from them as possible. If you cannot all together avoid the manipulator then protect yourself by limiting your exposure to her. Manipulators are masters at knowing what pushes your buttons, so to keep yourself from reaching the boiling point, excuse yourself from the conversation and her presence when possible. Don't invite a manipulator into your home unless you are willing to ask her to leave if she crosses the line.
Don't allow a manipulator to make requests by using underhanded tactics. Manipulators have a way of making requests that don't really seem like requests. You will find yourself in the middle of a task that you didn't want to do in the first place. You will even give her money you don't have to give. Many times manipulators will drop hints, use bribery, guilt, or flattery to get you to fulfill their requests. Flattery especially works on innocent men who have low self esteem. She may say, "You are exactly what I've been looking for all my life," and he will fall for it. Manipulators are really good at turning on the tears to make you feel sorry for them. You will give and give not knowing they are laughing all the way to the bank. Manipulators have a way of getting what they want and they never look back at the people they have viciously taken from.
Learn to identify passive-aggressive behavior. Manipulators are masters at making their efforts seem innocent when they have ulterior motives. Their behavior usually ends up making you angry. When you get angry at them they will turn it around, placing blame on you for their own retaliation. Manipulators loudly proclaim their innocence and the insignificance of their actions while you come off looking unreasonable. Hard as it may be, ignoring these tactics will lesson the manipulators power over you. She may say she is sorry, but you have a suspicion that her words mean nothing. Here's a clue - they don't! Always trust your gut feeling. If you think you are being played, you most likely are!
Learn to identify the bluff. Manipulators are excellent at bluffing and they are good at knowing when you are bluffing. They will go as far as to threaten their own life (or yours) to get you to bend. The best thing you can do is hold fast to your beliefs and carry through with what you say. Avoid being vague. Be very clear with what you will and will not allow in your life and in your home. Giving in to threats will only strengthen the manipulator's control in your life. She is like a snake who will tighten the hold every time you give in. Eventually she will squeeze the very life out of you. Manipulators are dangerous and their constant control can be a detriment to your health.
Don't be the manipulator's victim. Manipulators are good at making their victim look bad to others. They will stop at nothing to look like the innocent one. They will lie, even under oath, to get their way. They will use subtle digs that seem innocent to others, but their victims always know it is directed at the them. The victim can speak the truth, but bystanders will actually believe the manipulator because she is so good at what she does. Understand that others don't know the whole story and it can be quite frustrating when the manipulator has everyone around them believing their lies. The manipulator only tells one side of the story and it is completely fabricated. If the people around you don't eventually see her for who she is, then they were probably not worth your time anyway. It's a never-ending cycle to be involved in a relationship with a person like this. It truly is a game to the manipulator. You will constantly feel that you cannot win, but the way you win is to get out!
If you lend something to a manipulator, be prepared to let go of it. Manipulators only care about themselves. They don't care about you or anything that belongs to you. If they know something is special to you, they will use it against you. They will take what you have loaned them and further use it to control you. If you must lend something to a manipulator, get a detailed agreement in writing. Even at that, don't expect to get your items back in the shape they left your hands. The manipulator will tell you the story she knows you want to hear, but there is always a hole in every story she tells. Don't believe anything she tells you!
Don't let manipulators do you any favors. Manipulators will use kindness to further their agenda. They may buy you gifts or write you letters in an attempt to get you to lower your guard. Don't be fooled by these attempts. They are only mechanisms to control you in the future. Never let your guard down no matter how sweet she acts, it's only venom disguised as honey.
Anything you say will be used against you. The less information they have about you and your plans, the less control they can exert and the less chance they can use what you say against you. I had to learn this one the hard way. The manipulator who married into my family would come and want to have 'heart to heart' talks. Before I realized who and what she was, I would pour my heart out, only to realize later I had cast my pearls before swine. Everything I said was used against me in conversations with other family members. Manipulators can never be trusted and they will never keep your secret.
Never justify yourself to a manipulator. Don't waste your time! They don't care about you or your time. Don't explain yourself because they will only use those words against you later. Let your yes be yes and your no be no. Learn how to be assertive and stick up for yourself. Manipulators will try to come across in a humble way, but their plan is to roll right over you. These people are sneaky and they will stop at nothing to get what they want. It appears in many cases the manipulators don't seem to have a conscious.
Stay in control of your life. Manipulators thrive on making others their doormats. You can't control what other people do, but you can control how you react to their behavior. I should have stood up many times and told the manipulator to leave my home when she overstepped her bounds. Never again will I allow a manipulator to control any situation in my life that I have the power to stop. If you cannot completely remove this person from your life, do your best to keep your time with her to a bare minimum. You have to resolve within yourself that you do not care what other people think about you because the manipulator will make you out to be "mean." Just remember that if you allow a manipulator to continue controlling your life, you will end up with a lot more pain when the dust settles.
(Some of this info was found on Knot-Heads.)