The only way a co-worker can take your ideas if you tell them your ideas. It’s simple in theory that you have to learn that you can’t share everything with everyone. This isn’t just with work relationships but its a principle to apply to most people. That doesn’t mean that you can never tell a soul what you are going to do, it just means discernment.
You don’t need discernment if the co-worker takes your ideas and uses it as his or her own. That’s called don’t get burned again. Like Maya Angelou has warned us all, if someone shows you who they are believe them. I like a lot of my co-workers but unless I have gotten to the point to bring you around my inner circle or family than I keep work relationships at work. That means yes we can go down to the lunch room and chat it up. Yes we can laugh at corny jokes. What that doesn’t mean is you can be on my social media. No you can’t talk about your man and his issues or at least you can but don’t look for me to spill my heart out to you. It means I am a full team player between whatever my work hours say I need to be. However to sit and tell you things and I can clearly see you are about yourself is a huge NO NO.
You can either mention the breach in confidence if its brought to you but often times I would just leave that alone. I would silently mark them and disengage outside of work chit-chat that you are obligated to talk about. I wouldn’t sit talking about anything with an idea unless your whole department is together and they hear it from you themselves. Trust me there is a club in most places of employment. This means if you don’t pay your silent memberships you can be an outsider. I know that no one wants to be an outsider and being connected can feel great. The key is the right connections and not just connecting your caboose to any old body. Learn to be okay being a team player and independent. You are at work to get your money and make your own personal dreams come true. Sometimes that may require some head phones and a smile.