I bought these Hoya hearts as a cute little house plant this past February. They have been doing well with casual waterings (as seen in first picture) but now it seems one has gotten darker in color and the other now looks pale green and has a brown spot! See second picture!! Please help!

Does your rock/pot have a drain hole? Hoya are epiphytic, they don't normally live in soil. The soil needs to dry quickly after you water. I suspect you have been over-watering.

It takes much longer for Hoya kerrii to grow roots when there is no vine attached to it. Some do say they are able to root just the leaves, but I have never been able to do so.

As already mentioned, Hoyas are epiphytic, so I am thinking it is being rotted from being buried in soil. If it were mine, I would see first the condition below, if it is still staying firm, then try to repot instead using orchid bark mix, or clay rocks...but do not use soil for this one.

There is a small hole in the bottom for drainage, however I did move the pebbles on top and noticed the soil was quite damp )): I'll for sure be re potting it, thank you so much!

What ended up happening here!?!