At some point in your career, you'll encounter an overly-bossy colleague. 'Bossy' can be a problematic word in itself, but you'll know the real thing when you see it. I'm talking about the person who's at the same level as you, that acts far above their station and assumes the role of a superior.
They may dictate how, what and when things should happen, or they may start trying to delegate their own work to you. You shouldn't overreact to the situation, but nor should you just sit back and accept it. There are ways you can deal with their behaviour.
Always stay calm. Yes, it's frustrating being told what to do by someone who doesn't have the authority, but getting short-tempered over it can backfire. Bossy people thrive on getting that sort of reaction, so lead by example, speak politely but firmly and show them respect.
You can show politeness and respect at the same time as being direct with them. Avoid blaming them, but explain how their behaviour is making you feel – for example, “I'm not comfortable with the things you're asking me to do, I would rather the manager delegated tasks like that”.
Finally, in order to bring some balance to the relationship, you could try the tactful approach of suggesting you collaborate more closely. It may grate, forming a closer relationship with them, but by collaborating you can lay down a few ground rules and ensure you both know where you stand in terms of dividing up work.
Bossy colleagues are a pain. Deal with them quickly, before they make your working life difficult.
Always stay calm
Lead by example
Be polite and respectful
Suggest a more collaborative relationship