Lucky you living in Laurel Canyon!
What you have is a container with three septa rooted cuttings of plumeria. They are all separate trees. They can be separated if you like.
Every V made by the branches signified that the plant has bloomed. Plumeria do not bench unless 1) they bloom or 2) they suffer some mechanical damage and produce a new branch from one of the old 'eyes' that used to have a leaf on it.
Yes, this is the period of dormancy for these plants. But when the weather warms up and rain starts and the day length really cranks up they will go into active growth.
This is the time that you should fertilize your plants. Don;t worry that the little leaves on the tips are black. They probably just got a little too cold.
Plumeria are hardy to 32F. They are succulent tropical trees and the stems will be damaged by freezing weather, and then they will develop rot.
Just leave it out on the deck as long as it snot frosting. Fertilize it with something like 1/2 strength Miracle Grow every month until it starts to wake up. Plumeria very often develop bloom spikes on the dormant stems BEFORE leaves start to come out. If you see something coming out of the center of those little black leaves, it may be a bloom stalk. The ends of the stalks will start to turn green as they start growing. Soon you will have leaves!
Your plant is not 'mature', its only a few years old. I would say 3 max. based on the number of times it has branched. This is what a mature plant looks like
