Using a Mr. Clean Magic Eraser, just scrub at it for awhile and wipe away any excess water. Keep it up for about thirty minutes and you will see al lthe pen marks starting to fade. It takes some time but it will work after awhile. same thing happened to me!
I recently learned that straight up ethanol or isopropyl alcohol (rubbing alc) will remove ink, and this can be used on your couch. I have used it on other cars w/leather seats to remove pen stains, and it didn't damage the seat at all.