I watched the Netflix Dark series. There are many unanswered questions, but indications are given to speculate. But I did not understand painting story.
Many times, Jonas' father appears with paint flowing over his face and paint coming out of Jonas' ears.
What does it mean?
It seems that Michael Kahnwald (Jonas' father) was a painter - or at least he did some paintings, as we can see multiple painted canvases in their attic. No more is explained in the series about that.
P.S.: if you did not finish the series do not go searching for characters' stories or plot explanations, there are many twists that might spoil the whole mystery! Be warned!
Personally, I interpreted this as blood all over Micheal Kahnwald's face indicating that Jonas was seeing a ghost/dead person/he wasn't real etc.
I saw the blood as also representing Jonas' fear of his father's death. It's mentioned a couple of times throughout the series that Jonas spent a few months in a Psychiatric hospital after his father's suicide, the bloodied visions of his father could be a 'physical' embodiment of the psychiatric issues that he was having.
I never noticed it on Jonas so couldn't comment on that.
That's just my interpretation, I could be completely wrong and it is just related to his father being a painter!
