Be careful with their jump, its super fun but can quickly land you int the bottom of tge rock drake caverns. If you aren't familiar with the area its very difficult to get out of especially with the radiation.
Here's how reapers work: Whenever they're at low health, they pick you up and shove their tail into you, injecting a symbiote into you. It lives in ur intestines until the time comes when it burrows out of your chest and runs away. Let's face it, it's the most unique way to tame a creature.