KeepingALevelHead on "Stain ID request- fecal or something else (dirt/pen)?"

Hi experts-
I found a stain on my bed- it started out as a black dot with a thin line that was about an inch-inch and half. I used some water to see if it would smear (smear test?) and it didn't- actually some of it washed away. In the picture below, if you zoom in, you can see where the black dot started and the trail of the rest of the line. These are all pictures of the same stain from different angles/flashes/zooms. This is the picture of what was left behind. I'm out of bed bug blue and still on high alert after a trip- could an expert let me know if this looks fecal related or is possible something else (maybe dirt or from a pen?)
Thank you!! Much appreciated
https://www.flickr.com/photos/135034946@N02/26135959216/in/dateposted-public/
https://www.flickr.com/photos/135034946@N02/26095549131/in/dateposted-public/
https://www.flickr.com/photos/135034946@N02/26095548971/in/dateposted-public/
https://www.flickr.com/photos/135034946@N02/26135959306/in/dateposted-public/
https://www.flickr.com/photos/135034946@N02/25889022620/in/dateposted-public/
https://www.flickr.com/photos/135034946@N02/25559262033/in/dateposted-public/