Guys, with all due respect: Do NOT redraw over an artist's art without permission

Please ask for permission. Cause making art for someone and them literally drawing all over it to change basically everything (mostly when I'm doing it for free out of kindness), is just so disrespectful and offensive. 

Now I feel like I did a bad job or they aren't happy with it. Makes me reconsider why I'm doing it in the first place, if they can just draw it however they want.

It might just be me, but it genuinely bothered me