Leather questions

My little hurricane strikes again ! You simply can't let her hold a marking pen because she is sure to hit most of the areas in the house. I know she has the talent in doodling and drawing, but I want her to keep in mind that she can only do it in her papers. Anyway, she got a few lines in our leather couch and I need to have some quick fix with it. Anyone here who knows how to dye leather ? Ours is in cream color so you can really notice the blue marker used. I am not hopeless, I know that there are really good ways to treat a leather, i just need to do some research.