Acanthocereus tetragonus ‘Fairy Castles’ maybe? if so, it's a diminutive form of Acanthocereus tetragonus. I've read it's very unlikely for this form to bloom.

You’ve got a good ol’ Cereus repandus aka Cereus peruvianus cactus. It could also be a Cereus hildmannianus, but I don’t know if there is a huge difference tbh;). Here’s a little Info:) on why there is confusion. Edit: I just looked at the Arizona State University’s public page on Cereus repandus and Cereus hildmannianus, and it says that hildmannianus has “Stems grayish to glaucous”, it doesn’t say that for repandus. So I’m guessing that’s your cactus;). The coloring is the only difference I spot between the the two cactus in question on ASU’s site about the two cactus.

that's crazy! I have the slightest feeling it may be epiphyllum because I have a vague memory or the parent being a draped plant but I coincidentally did a post before this (not sure if you can find it thru my name) and it turns out I have another upstairs. the this plant is just so thick I can't imagine in hanging. what can I do to accelerate its growth? or is it just such a slow growing plant? I do recall the other upstairs taking years to do much and all the sudden it just took off and won't stop growing!

Noah, soon you'll be ready to cut that etiollated piece off and start a new plant with it (also, the original plant will grow out of it). That's, of course, only if you want to rid the plant of that curve. Normal growth will resume with enough sun. It's a nice plant. Pilosocereus have some of the bluest colours available, along with lateral wool and cephaliums and flowers smelling of freshly-shucked corn.