Pretended to have a malignant brain tumor for over a year in order to coerce me into having sex with him.
I was 13. He was 16. After pursuing me for months, he became my first boyfriend. A month into the relationship, he tells me he's been diagnosed with a malignant brain tumor and has two years left to live, and I'm not allowed to tell anyone because he doesn't want their pity - he's only telling me because we love each other. As the year progresses, he developed some of the symptoms - talked of frequent headaches, bloody noses, temporary paralysis, and I observed myself that his mood frequently oscillated between extremes. It was very hard to deal with. I, being the idiotically infatuated 13 year old that I was, was determined to be a good girlfriend and support him as long as he was there. I frequently worried about him so much that I developed headaches from frowning. 11 months of this later, he tells me that he doesn't want to die a virgin, and because he loves me so much, he can only lose his virginity to me. The almost-14-year-old. We almost fucking did. But he bragged about it to some friends, who told the principal, who ended up calling my parents in for a special meeting, which landed me in the most trouble I've ever been in. I come from a conservative family, so I wasn't supposed to be dating anyone, much less someone 4 years older than me, and I especially wasn't supposed to be trying to have sex with them.
I have to say, pretending to have a brain tumor for a year takes quite a bit of commitment. He even went so far as to pretend he got a second, negative diagnosis from a hospital in a country with better healthcare. Then, a month later he tells me he lied that so I wouldn't worry about him. He had a (fake) brain tumor all along.
And years later, it's a funny weird story, and I can spot a manipulative person from a mile away. But at the time, he caused me anxiety and pain, and then got me into huge trouble for deceiving my parents (which filled me with a sense of guiltiness that has never gone away), and then harassed me for my choice to break up with him for months, all while holding suicide ("I'm dying anyway, might as well speed it up" was frequent) and his tumor over my head.