For anyone confused, "The Hot Professor" is now titled "The Light to His Dark". Keep reading for an explanation.
As revealed in chapter 8.5 and moreso now in chapter 13, Brian clearly has his own issues, some revolving around his mental health. Dan is a kind of beacon of hope to him, a light in the darkness he constantly feels suffocated by. Dan could be the one to help him and guide him out of the harmful mindset he feels trapped by.
At the same time, Brian is a light to Dan's darkness. Dan has his own issues, lightly hinted at throughout a few chapters. He's also less than enthusiastic about being in Brian's class. Brian is a type of inspiration, a reason to keep pushing himself to Dan. He's the reason Dan tries. Now that they're almost a thing, Brian may be able to show Dan what he's capable of and push him to find his limits.
I thought the title was able to encompass the feelings Dan and Brian have or each other, and the rather simplistic design of the cover draws the eye. As pointed out by a good friend of mine, green works well as a color for them, since Dan's coded color from Starbomb and NSP and pretty much anything else is blue, while Brian's Starbomb coded color is yellow, and blue and yellow make green. idk, the cover was fun to make.