Found in my garden:

Thanks so much for your reply! Someone on another forum was able to ID it as Euphorbia drupifera, and looking at the pics that's definitely it. The leuconeura is very similar to it though - that's a neat plant! Thanks again! :)

The one he gave me look like that yellow pods but the heat level of the that pod was not as strong as Thai. He did have other pepper plants but I don't know if they are the same or not. I tried eating one yellow pod out of the plant a couple weeks ago but realize it was too young, no heat at all and the seeds were still translucent. Now I'm waiting to see if those yellow pods will eventually turn red or not.

If there is growth that is discolored, dead, or no buds of any kind, prune it down to 2'. Flowers will only show up on the growth from the previous year. If you prune it every other year, it will encourage the flowers to grow more thickly. Eventually it will form a very dense hedge. It sounds like it may be in deep shade from the oak tree and ivy! Quince will flower more and produce more fruit if it has longer exposure to sunlight. If there is a very dense growth of ivy on the oak tree, trying removing as much of the ivy from the tree as you can. Ivy will eventually kill the tree, and it will block the some sunlight from reaching plants around the tree. You could also do a light dose of fertilizer to help your quince get re-established since the privet hedge and weeds have been choking it. Let us know what you decide to do, and how it goes!