Well, I love the Fox form of Adul. The bright colors captures my eye as well as the lop-sided ear. Its great to see non straight ears on a character. Lets you know that Adul can be playful and a great person to be around. I am not sure about the cone nose on most drawings, but you seemed to make it work for you. I hope this fox form was fun to draw.
The Adul as a dark assassin is dark and bold. he brings the attitude that he is not afriad and will attack. The fact that he is disintegrating shows how your drawings are improving and shows that your tapping into new artistic areas. Although you do not see green ears on many characters, this could be just my point of view of course.
Overall, great job. I am amazed by your artistic skills. You have shown that with more practice and the ability to explore more artistic styles, a better and more skilled artist you will become.