Mary is exactly the kind of person who I call a user co-worker, who uses whomever within reach to get the work done and then grabs all the credits. These users tend to have good communication skills and one reason is that they''''re truly so brazen, and often so shameless, that they''re never afraid of speaking up, making unreasonable requests, and asking for unmerited favors, well, which is exactly what users do. They use people.
The question is how to deal with these user co-workers, or how to protect yourself from being used by them. The keyword is "play" and just play along with them. Don''t ever ignore them because if you do, then you give them a reason to say bad things about you and you are unable to defend yourself. Don''t help them either, just decline their requests with a polite but firm "NO", and explain your reasons (excuses). Or just direct them to people such as their boss or senior colleagues, to whom their incompetence and true color will be exposed. Try your best to keep all these communications in written forms. Or in certain cases, just make a deal with them, as a quid pro quo, help is provided only if you get something in return, such as credits with your name on the PPT, etc. However, make sure you don''t put any of these interactions in writing (emails or texts) and make sure everything is done verbally vis-a-vis.