This is definately an interesting idea. What prompted it?

Hit Dice: D12
Is this a pathfinder thing?
I am only familiar with HD being from class or race and I see no mention of racial HD.

They are a race of humanoids whose veins contain the very essence of positive energy. Their blood, regarded as the Elixir of youth, prompted greedy tyrants to hunt them down and suck them dry, to preserve the life of themselves and other desperate nobles. And it really works.
I'd love to know how that works.

+6 Constitution, -2 Charisma
Trueblooded have incredible vigor due to their miraculous blood, but take a hit to charisma for their off-putting appearance.
That's a pretty major bonus for any LA +1 race, but you have some hefty drawbacks as well, so...

Scarlet Vision (EX): The Trueblooded can make his eyes glow with red light as a swift action, dimly illuminating everything in a 10 foot cone in front of him. While in this state, the Trueblooded has Darkvision out to 60 feet in front of him, and cannot gain any type of Concealment against non-blind opponents. Closing this racial ability requires a swift action.
Interesting take on this. Put's a fair sized cramp on stealthy types.

Gift of Blood: Whenever a Trueblooded gains a level in a class, he rolls a dice that is 1 step better than the class hit die (d4 to d6, d6 to d8, d8 to d10, d10 to d12, d12 remains unchanged).
I'm always curious about arbitrary dice cut offs. It seems like it would be simpler to just give a bonus hitpoint (the average increase with a dice size increase) per level and it would avoid the need for a seemingly arbitrary cap.

Frantic Metabolism: The Trueblooded must eat much more than normal humanoids to keep himself healthy. Treat his requirement of food and water as if he was 2 size categories larger.
I like this, but it is a really group specific thing. If a group ignores food requirements then this isn't really a drawback at all. If the group does track it, that adds up to a lot of upkeep.
Maybe a special material food requirement instead like an ounce of silver (a pure element) per day instead?

If a Trueblooded gains a class feature that permits him to no longer require sustenance (like capstones that turn you into an outsider), he (reatroactively) loses all his racial bonuses (including the +6 to Con, but excluding the -2 to Cha).
So they have no favored class, but they have a racial feature that completely destroys the worth of some class features.
How does it work with magic that removes or alters sustenance needs?

Essence of Life (Su): Although it's a bit unintuitive, because Trueblooded are beings infused with positive energy, they actually cancel out negative energy that would affect them, but an imbalance of positive energy can bring them much harm. Therefore, they are immune to Negative energy but vulnerable to Positive energy, another thing which made people over the years mistake them for vampires.
This I really like, and it is a major drawback with magic healing.
How does it work with other positive energy effects (turning undead, hallowed areas, etc...)?

Scarlet Restoration: The open wounds of Trueblooded, just like their blood, glow with a dim yet easily noticeable shade of dark red. The positive energy in their body, by seeping out, reinvigorates and heals their wounds. A Trueblooded keeps track of Slashing and Piercing damage separately from other types of lethal damage, and has Fast Healing 2 against these types of damage only. Additionally, a dying Trueblooded is always stable.
More tracking to do. Why not a some form of damage reduction (maybe 2/bludgeoning) instead?

Wailing Blood (EX): The Trueblooded put great value in their own lives and go to great lengths to ensure their own survival. Any Trueblooded below 1/4 his max hit points, rounded up, gains the ability to communicate telepathically with all intelligent creatures up to 1 mile away from him. Those he contacts cannot answer him back, but become aware of his current location. However, this is not a compulsion, and they may come and help him only if they want to.
I like this, but it is definately a two edged. Some of those other creatures might like having an easy target. I like this, but

Channel Energy (Su): When touching an opponent, a Trueblooded can infuse him with his own Positive Energy, in large, harmful quantities. A touch attack is required for this to succeed, and the target takes energy damage equal to xd4, where x is the Trueblooded's HD. Then, the target becomes immune to this ability for 24 hours, and the Trueblooded becomes fatigued for a number of rounds equal to the number of times he used Channel Energy that day. While fatigued or exhausted, a Trueblooded may not use Channel Energy.
I would never use this, but given that this is a positive energy effect, shouldn't it have greater efect on undead.