Find another group. Finally, I hope that you know you are free to come to me anytime to discuss anything that concerns you. I sincerely and genuinely care about every one of my students, and will do whatever I can to make your academic experience as rich and rewarding as possible. However, because I enjoy my students and have fun working with them does not mean that my students can take liberties with me. Specifically, if you are a research student of mine, and also a student in a traditional course that I happen to be teaching, you should not expect nor try to obtain special treatment, favors, etc. from me with regard to course work in the traditional class.
Research is research, classes are classes.
The two are separate and distinct. A more relaxed research atmosphere is essential to the creative flow of ideas. Do not mistakenly assume that the classroom atmosphere will automatically be the same.