Oooh, yes. Amazing series. It's terribly long, though and the focus is Ripper / Ethan although Ripper is at first drawn to the non-canon roommie.

Oh, you know what. I wasn't thinking of Of Old Mystics although that's an excellent story too. That mostly happens after Giles rescues Ethan from The Initiative. I was thinking of In the Morning of the Magicians: https://www.notanothersite.com/indri/morning.html

Part of me wants to post it to AO3, giving credit where it's due of course, but some people tell me that's not cool even if the author(s) are no longer online.