I took a close up of area I was talking about. Didnt knoe how to add to original post and post this pic.

Can you put a ball of yarn on top of it...or a mouse??

I think you are being over critical of yourself. Once you get it hanging on the wall, I really don't think it will be so noticable. But if it really bothers you, maybe you can sew a ribbon on it and tie it in a bow, like the cat has a bow tied on it's tail.

Is this fusible applique?

One has to look very hard to see it.

If it's a wall hanging, I think I would leave well enough alone.

I'll agree with over critical, you really have to look at the photo to see it, and when its quilted it just might blend in :)

I agree - just leave it as is and proceed with your quilting.

once it is quilted you will never see that joint- and remember- all applique has pieces (come together) yours is as normal as anyone elses- finish it up- quilt it- it will be ok=
one of the big uses for design walls is so you can put your work up and then step back- if you can not see something from 10-12 feet away- it is not going to be noticable when it's all done....sometimes we are just too (up-close)
relax and continue on- you are doing fine

Are you 'set' on having the cat solid black? You could applique a few spots/blotches and make him a calico.

or (what I would do) is extend the end of the "yarn" with bias tape, or maybe even real yarn for texture, and swirl it a little so it trails up and over that section, stitch it in place.

Thanks everyone for all your suggestions. I did think I might put a ribbon or something,but I just dont know.
Those of you who suggested to just quilt it, did you mean to do free motion all over his body? I thought to do that, but didnt know how it would look. Well thanks for all your help.