I started my current role a few months ago as an analyst, joining another person who had started one month before me, with the very same job title. He's two years older than me, but he treats me like he's been working there for 20 years, and like he's my boss.
He always asks me when I'm going to complete a task, and when I answer by saying "I'll hopefully get it done by tomorrow", he'll say something like "don't say hopefully to me, I want a straight up answer".
He also chews me out in front of other people in the office over really minor differences in practice that we have. If I write a piece of code to quickly show him something on screen, he'll almost always say "why are you doing it that way?" in a condescending way.
I honestly believe he has detected very quickly that I'm a meek and mild person, and now he's exploiting that to boss me around.
Our actual boss is based in Paris, whereas we are based in London. I would have talked to my boss about it, but as you can imagine he's not actually around for me to talk to him. He's also very busy all of the time and essentially has my colleague and me on autopilot.
I'm at the point now where I want to leave. I've asked my old boss for my old job back, and he's essentially said yes. But my current role has a notice period of 3 months. I'd quit tomorrow if I could.
Should I try talking to my actual boss about it? If so, what can I say to fix the problem and not make it more awkward with my colleague?
EDIT: After this question was posted and I read the answers, I started being a lot more assertive and stood up for myself, and this approach worked quite well.
He's still difficult to work with, and for that reason I accepted the offer from my former boss.