How did the cactus look like beneath the curtain?

The majority of us assume the person speaking behind the curtain in the Z rank room in chapter 3 IS the tsundere cactus upstairs.

Chapter 5, in a way, confirmed that when a fountain is opened, the flowers are allowed to fantasize a higher level of consciousness. The forms they take in the dark world are manifestations of how their dreams reflect on their characters.. Which is why Orange is a rat despite the fact the flowers' presumably all agreed to take on the forms of humans in their dreams (according to break dialogue found in the Flower Cafe)

So, if we assume this applies to ALL plants and not just flowers... In order to discover anything about the cactus we have to discover what it's dream is.

We know because of a recurring gag originating in Undertale, that cacti are sharp on the outside, but soft on the inside. Making them a tsundere. Also known as "a word you liked."

We have dialogue from a pippins saying something along the lines of "the cactus upstairs loves you" which further solidifies that it's soft side is presumably caring for Kris. Kris also happens to have been the one to open the TV World fountain, so it COULD be possible that it's dream is to care for Kris, like the 7 colored flowers with Asgore.

There's also another voice speaking behind a curtain. If we assume that this is ALSO a cactus then this one's dream is likely to have a maiden (the mizzle inside the watercooler)

Also the cactus in Tenna's first board seems to blush once you push it, this could imply that the cactus's feelings towards Kris might be *somewhat* romantic..?

The cactus, who loves Kris, blushing when you push it, could be a parallel to Pushing Buddies. Which is called "`tvromance`"

(Kralsei confirmed?!)

Now do keep in mind that the whole dream thing could only apply to flowers and in that case this entire theory goes through the gutter

In conclusion: The cactus behind the curtain could likely look like...

...

...Ralsei..?