What is the best eyebrow filler?

I have nice eyebrows but I just wanted to fill them in. I probably don't really need to but I want to because if you look closely you can kind of see sparse areas. OK, I have dark brown almost black eyebrows. I wanted to bleach them like 1 shade lighter. will jolene bleach be ok? And what is the best filler? should i use a pencil, gel, or powder? And what brand and color should I use?? thanksss