Actually, this one isn't all that hard to figure out. Probably wondering "why" this is the assumption the senior dev is having. The senior dev obviously believe

Actually, this one isn't all that hard to figure out. Probably wondering "why" this is the assumption the senior dev is having. The senior dev obviously believes you have been hired to help offload or relieve some of the work going around. What I have seen in this industry over the last 20 years or so is that this may or may not be true. Upper management needs to clear this up- for the senior dev. As for the other issue "can't understand simple logic" consider this is a personality trait for some developers and not a judgement call. There are some developers which require 100% of the information just to get started and they still will act naive because that is who they are. My advice is to not try and change personality traits or spend a lot of time teaching a lesson here because that could take years. Yes, you read that right YEARS and still not get the result desired. The last one "he acts like I don't know anything" probably is more likely "he cannot figure out how to delegate the work". Again, another upper-management thing and not your problem at all. So- either talk to him or "the group" but roles need to be clearly defined. Once this happens you will be onto the next set of hurdles- good luck!