cast a shadow over (one)

1. To dampen, spoil, or ruin one's mood or outlook. The coaching scandal has cast a huge shadow over all the athletes on the team. The way my ex-wife treated me cast a shadow over me for several years. The headmaster's sudden death really cast a shadow over all of the graduates.

2. To make one feel less significant, important, or unique by comparison. My dad was a famous movie star, and that cast such a big shadow over me as an actor that I'm still trying to get out from under it. The teacher mentor said that he would be staying out of the spotlight so as not to cast a shadow over the students and their work. I didn't want to go to the same high school as my genius sister because I knew she would cast a shadow over me.