The plot?

I believe he's the father of the purple-haired kid.

Lying on the internet I see

We don't know what Mr Lee and Cirrus have been discussing together recently, but we know they have been seeing each other quite a lot during school time outside of class, so now i suppose the author is using Mr Lee as '' the one and only adult who cared '' in the life of Cirrus. But now isn't 3rd year already over ? Are we not past the last exam already ? I think ? So is Mr Lee going to play a role outside of school and is going to play a positive role in helping Cirrus ? Is he going to mentor Cirrus or testify for him or something ? Mr Lee probably understood that Cirrus and Skylar have a special bond after what he saw and heard recently. So we will see what the author wants to tell us with that character.

Lol _ ha ha who knows !! :-D