Because being a red you are NOT a friend of a goodie goodie like a fairy... You are an Imp...You can do both quests as a red, done it many times, Arielle can be found at the fel spirituality shrine, it's just the friend of fey quest for spellweaving you can't do as a red.
they put in an arielle near the felucca sacrifice shrine
OMGosh!!!! I've never met someone else who says groovy! So groovy!!!! Sorry, got a little excited there.Groovy ..... that helps alot