Yeah in the mini chapter at the end of Volume 2.Come again?
After the big fight where Chloe befriends Shoggoth, the whole group goes out to celebrate with a big dinner courtesy of the Director Nyarlathotep. Spurred on by Dr West to drive the price up to stick it to Nyarla, the whole group proceeds to get shit faced drunk.
Chloe then gets super horny, comes on to Shoggoth...and they wake up in bed together. I mean it's not specifically stated that they actually DID it (it actually states what really happened is an eternal mystery), but it certainly looks that way.
Here it is if you want to read it (remember to read it left to right though).
Chloe be Bi as fuck.