I'm not good with IDs, perhaps a cremnosedum? One thing is for certain, keeping it in a teacup with no drainage holes will likely kill it. tj

This one is Solanum dulcamara, Woody Nightshade or Bittersweet. The berries remain red, unlike S nigra and its cousins which have black/dark purple berries. Edibility on this particular species is not controversial - all parts are poisonous.

No fertilizer, please. In fact, the next time it needs watering, you should flush the soil thoroughly to eliminate the potential of a high salt level in the soil. If the plant is suffering from high soil salinity, fertilizing now could be its undoing. It's likely it's been badly over-watered, so I suggest you make sure your watering schedule is appropriate. That's a long way of saying "Only water when the plant actually needs water." I think that's where you're going to gain the most traction when it comes to pulling it back to a higher vitality level. In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material like clay, or when the weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water. Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, this type of situation cause the loss of a very notable degree of potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'. One very reliable method of checking a planting's need for water is using a 'tell'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a pin. Push the tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw and inspect the tip for moisture. For most plantings, withhold water until the tell comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue. Many of us flush our soils whenever we water because the soils we use allow us to do that w/o worry the soil will remain saturated so long it roots are robbed of oxygen for extended periods, which limits root function/efficiency and can wreak havoc with root health. If our soils DON'T allow us to flush at each watering, we need to figure out a way to flush often enough to ensure salts from tap-water and fertilizer solutions aren't accumulating in the soil and limiting the plant's ability to take up water. To flush the soil of a planting: Water with room temperature water until the soil is completely saturated. Allow the planting to rest for 15 minutes to an hour to allow as much of the salt accumulation as possible to go into solution, then pour a volume of room temp water equal to at least 10X the volume of the pot the plant is in slowly through the soil. This will remove most of any accumulation of offending salts and resolve any skewing of nutrient ratios. If you decide to flush the soil of your plant at the next appropriate opportunity, ask when that opportunity will be, and how to mitigate the potentiality of prolonged soil saturation after the flushing op. Al

It's a heart-leaf philodendron! It has similar care to a pothos, indirect light and water when the soil is dry.