My colleague has a strange way of answering things, When asked about something, he would be "That is my job, or my side of work/coding. Don't need to worry about that."
So it had me asking myself, should I share my knowledge as when my colleague is over, he would not tell me his part of code rather a quick answer like copy paste and would ask me full description of what i do, and what does that.
It is a sign that I shouldn't share my knowledge or contribute to documentation (as my peer wouldn't and me and my PM are the only person who does).
Whereas my peer is very keen to know, what I do, and want to defend his way is better (because he think my job skills rest with him too e.g. he is a dev and a i am designer).
How open should be about my task with him and open to him, as he likes to put it. "Don't worry it is my problem or my portion of code" but would ask me, why and how for my code even he doesn't know basis.