I've noticed for a while now that somebody at work keeps sending a list of chores for other people in our subteam to do then she blantantly says infront of our manager that she did them. This has been mainly little jobs so it never seemed like something to bring up.
Yet, recently she's been tasked with writing a report about a series of events our team ran, and she sent me a massive list of data to retrieve and compile which is not a light job. Knowing exactly what she was doing, when I finished all the data, I sent it to everyone in my sub team, only to get a not best pleased message saying she wanted to add it to her report before sending it to everyone. Convenient. Bad luck. Good old passive agressive tactics come to the rescue.