There were/are students in my department like the ones aristophanes mentioned, and early in my grad school life, they scared me to death. It seemed as if they were soooo accomplished, and I felt like a colossal loser compared to them. But then I realize that most of it is just talk. All I'm saying is that if a grad student can't walk the walk, then perhaps s/he should zip his/her lip up a little bit. Maaybe? Just my thoughts.
Maybe. In an ideal world, people wouldn't brag about stuff they haven't done. Although I have to say, if someone asked me not to present myself as confident in my abilities because it makes them feel like a loser, I don't think I'd be willing to oblige that request. While I know that I have a lot to learn, I am confident of the abilities that I do possess. Why should I pretend that I'm not?
And anyway, the OP isn't going to change the colleague's behaviour. Besides, from the OPs posts and comments, it sounds like this particular colleague
is walking her talk. After all, she knows the material well enough to impress half the faculty. It also sounds like the OP is a little jealous and bitter that the colleague is getting credit for walking that talk, since the talk that is being walked was initially the OP's. Fully understandable, and I would be jealous and bitter, too. But that doesn't make the colleague a braggart who doesn't know her stuff. Maybe she really is that accomplished. If not, she's certainly pulled the wool over quite a few people's eyes, and has been doing so for a very long time.
This colleague did a nasty thing. She stole the OPs ideas, and passed them off as her own. But why didn't any of the senior faculty realize that another grad student was already working in that area? How come no little bells went off in the chair's head... "now, isn't that student... what's the name? Aristophanes?... the one working with Professor Brilliant... isn't that student working on something similar?"
That tells me that the OP has got to step up and start playing the game.