When your coworker is a credit thief
Some people have mastered the art of looking busy while secretly looking for ways to steal credit from those who are actually doing real work. Don't get me wrong; they invest a lot of energy in it, and it becomes a full-time job, but it would be more ethical to invest all that energy into actually working.
They'll be the first to volunteer to present work and say, "We've been working so hard on this," while everyone thinks: "We?" At first, it might go unnoticed, but reality always catches up to them, and everyone on the team ends up hating them and/or taking revenge.
Many office achievements are reserved for those who successfully advertise their accomplishments, not necessarily for those who objectively accomplish more.
These credit thieves are generally very quick to put the "I" in work they never participated in, and even quicker to throw a "we" when there is a mistake. It's all about enhancing their good qualities and hiding those not so good. We all do it, to some extent, but there are limits.
They usually take advantage of the fact that not many people like conflict or confronting others, and they use that to thrive. But if they steal credit long enough, it will likely backfire, and when it does, every team member will be there, happily watching.
At work, your intellectual credit can grant you a better position, more responsibility, more money, and many other cool improvements. The thing is, eventually, if a credit thief gets any of those, they won't be able to perform at a higher level, and that's when the mask will drop. You can't steal your way out of work as you go up the ladder and take more responsibility; at some point you are going to be confronted with actual work, and you won't know what to do.
I have to say it, I actually believe in confronting people, and I don't understand why it has such a bad reputation. I've done it many times, and when you do it on time and assertively, it can save you years of stress and petty fights.
I used to have a friend in college who copied my every move, to the point that it became weird to everyone but her. At first, I didn't say anything because I thought it was my imagination, but when it became evident, I immediately brought it up to her, and it was like the spell was broken. Of course she denied it, but it probably made her so embarrassed that she dropped it the next day.
Confrontation works wonders, if you do it well. If I had to give you advice on that, I would say you have to be very respectful and try to keep it short and to the point. The most important thing is that what's bothering you stops being a weird taboo that grows without anyone noticing.
Once you put it on the table, you can do something about it. So good luck confronting anyone you have to confront!