Appearance and Physical Traits:
Half-Dragons are surprisingly similar to their non-dragon parent. it's comparable to simply have a normal being and just adding dragon parts if you want the proper effect.
In any case, the half-dragon will almost certainly be covered in scales, have sharp claws and teeth, and slitted eyes, but the rest is unique to that particular one. An individual might have have a human-like head, while a sibling could have a head more akin to that of a dragons. The most likely body parts to be different from the base are extremities such as hands and feet, the head, a tail, and wings, though other changes may be present.
There are also less visible differences inherent to half-dragons. The first is vocal range; if they inherited vocal chords from their draconic parent rather than their non-draconic one, they will have a very wide range of tones, and will be capable of mimicking most voices they wish except for extremely low or extremely high pitch. Another is the Eyelids; True dragons have several sets of eyelids, usually three, each one thicker than the last. Half-Dragons only have two sets - one semi-clear one that cuts off the glow of the eyes from within and protects the eye while in the air or underwater, while the second is much like a human eyelid. when both are peeled back, too much light will hurt a half-dragon's eyes, but it allows them to see a great distance in the dark, even in pitch black conditions.
Another difference is the Draconis Fundamentum, which is likely the single most important organ in a dragon's body. attached to the lungs and heart, it also affects the stomach. It's an elemental furnace, based on the dragon's element; it can secrete elemental energy into the lungs for the dragon to breathe out. By adjusting the stomach, the roiling elemental energy breaks down almost any sort of matter the dragon wishes to feed on, allowing the dragon to subsist and nearly anything, organic or not. A dragon could literally eat dirt and survive as healthy as they might be if they were eating sheep. the Draconis Fundamanetum extracts the energy gotten in this way from the stomach and moves it to the heart, where it can be spread to the rest of the body - the remins of whatever was eaten are what the dragon urinate and defecate. Despite this, a dragon can run on what they eat normally if for some reason the Draconis Fundamentum is impaired - they will be forced to eat reasonable food rather than things like rock, and they'll be unable to breathe their elemental energy, and won't be capable of flight.
This organ also allows fire and electricity dragons to internalize energy from their environment - a fire dragon resting in a volcano will be capable of internalizing the heat coming from the magma in their home. This can make dragons seem hyper if they internalize too much energy, but it also means the dragon won't have to eat as much.
the final difference is that many Half-dragons have a genital sheathe. Nothing more on the matter will be said.
Skills and Abilities:
Half-dragons are a great deal stronger than their non-dragon counterparts, and at peak condition can lift more than a ton without too much strain. Because of their link to dragons, which are arcane beings, many also have magic as a sorcerer, getting such magic directly from the source. this isn't always the case, but it's certainly very common.
Birth, Life, and Death:
A Half-dragon's birth depends on the mother - if the mother is a creature that gives birth live children, the half-dragon will be born as such as well. if the mother is the dragon, then the Half-dragon will hatch from an egg.
Half-dragons age at the same rate that humans do until they reach somewhere around the age of twenty, though some may fluctuate more than others for exactly when their aging process slows down. after that point, they age at a rate of 1:5, meaning many human half-dragons will live to see their fourth century if nothing kills them before then.
Half-dragons share the genome of their non-dragon parent, which is the reason thy look so much like their non-dragon parent. what changes them to be like a dragon is the essence that gets transferred from the draconic parent. It adjusts the baby in the womb when it would otherwise be a normal creature of the non-dragon race. If this is understood, it can be a simple matter for a dragon to keep that essence from affecting an unborn child, using magic, though most either don't understand that or don't bother.