Have a Moderately Satisfactory Birthday, Severus...
...even though I know you are rolling your eyes at the idea of celebrating it.
Here is a piece of art I started a year ago and have not finished, but I thought I would post the partially finished thing in honor of the snarky grump's birthday. It looks very sketchy in this photo, but oh well. I suggest clicking to look at the details, which are better than the overall image at this stage in the process.
Here is the process I have gone through so far: I selected and cut out pages from several of the books that have important Snape moments on them. I mounted these pages on a canvas. I sketched and then painted the image in oil and acrylic (yes, both, I know...). I used a white pencil to write on the board. I left it sitting for a year and the paper has yellowed and warped. (I'll pretend that was part of the plan)
Here is my plan for completion: Add some watercolor washes on the paper. Make some major corrections/improvements with acrylics. Seal with a varnish, or possibly consider sealing with a clear resin, adding some texture in the layers.
Most of my motivation in posting this is that I will attempt to finish this in steps over the next few weeks and post the results (yes, Severus, this is a selfish, self-interested "gift" for you).