Sorry, but I do know about Hellblazer! I read them as they came out :) Tbh tho after the second season or so of Buffy I felt Spike evolved pretty far away from those Constantine origins. And reading this made me think about how much of the BigBad reformed/still mistrusted by the adults/ but strange empathy with some of the kids there is about him. And Joss was such asa hardcore X-fan it doesn;t seem too unlikely he plugged some of that in.

I did read the Magneto New Mutants issues but 100s of years ago so I'm not geting it from that btw - from these summaries.