Obviously :: chinscratches :: How close to you want them to be? Like, formerly bonded, or just friends who occasionally fought together? If the former, I'd suggest maybe Zoe helped her in the dopple-facedown and they both gained wisdom and went Oracle through the same experience... if the latter, then there could have been a pleasant reunion once she went Oracle later than Zoe did, and they kind of mellowed into a more adult friendship.