Tiefling

Tieflings are a race of humanoids, descended from demons and devils who had bred with humans long ago.
While they are not inherently evil, their appearance likens that of their ancestors, with horns, tails, sharp teeth, and a wide array of eye colors and skin colors. Some see them as bad omens or heralds of evil, though most see them the same as genesis with there elemental ancestors. Pacts for power or promises of greatest are the most common way that Tieflings can into the world, but some had more personal relationship with the infernal beings.    

Bloodlines

There are serval different bloodlines of Tieflings, which have slightly different looks but more importantly different magic and infernal legacy heritage. some people believe that they follow the 7 deadly sins, or the rings of the infernal plane, but that is incorrect.
Bloodlines are created through the different races of infernal beings, not the individual beings themselves. The individual might effect look or power level, such as a high being creating a more powerful kin while an underling creates a kin with weaker magic and another has kin with more demonic looks.
All Tieflings have inherited magic and natural charisma(+2). Different bloodlines give small boost (+1) into different stats.  

Asmodeus (Devils)

The most common of the bloodlines, Asmodeus has many followers who had made there was to this plane to cause chaos. Asmodeus shared power with his followers, giving all who were sired by their pacts a piece of Asmodeus' power. Asmodeus himself is located deep at the heart of the infernal plane and rarely answers calls. it can be hard to tell apart if one has a henchmen under Asmodeus for an ancestor or the devil himself, though the latter is very rare.
Within the devil's ranks are five (5) high level devil's who have started to make their presence known and possibly split from Asmodeus as a whole. So far though, The difference in offspring are not enough to warrant such a thing, though it is noted that higher level magic tents to be the difference.

Those with this bloodline have increased intelligence and are able to cast the spell Thaumaturgy and hellish rebuke. If your sire is one of the archdevils, there are chances that the hellish rebuke will do different damage then fire. Known are those that cast acid, cold, lightning, necrotic, and force.  

Beelzu (Demon)

Some say that they are the latest inhibitors of the infernal plane, others call them the weaker cousins of devils. What is known is that they are the largest group of infernal inhabits, but are not the most of Tiefling bloodlines. Little demons can often get mistaken for little devils, but demons are more likely to go to our plane for mischief then chaos. Beelzu is said to be the lord of the demons, a fly that watches over his people with a million eyes, but he does not control his subjects. This bloodline is vast but the common things that carry over is the race's sturdiness, wild colors, and brazen attitudes.

Those with this bloodline are able to cast the spell Prestidigitation, Thunderwave, and spider climb. They also have +1 constitution  

Vianthila

The bloodline of Vianthila consist of succubus and inccubus. while one might think that they would be the most plentiful of teiflings, but they are actually more uncommon. Vianthila was sometimes seen as an avatar for lust and desire, others saw them as a fallen angel. either way, they are always depicted as beautiful and graceful, though no one really knows if any of this is true or just want they want from the parent of all desires.

Those with this bloodline are able to cast vicious mockery, charm person, and enthrall. They have increased dexterity  

Tanzath

Infernal beings that our said to give bad dreams, or nightmares, they are often depicted looking similar to a house. those of this bloodline have power of sleep and the mind. they are more likely to have hooves, as well. They are also one of the rarest of the bloodlines.

Those with this bloodline are able to cast vicious mockery, Sleep and crown of madness. They have an increase in Wisdom  

Lusukini

Female demon race that are complete carnivores with two sets of arms. These fiends are beautiful but thought of as insane but to their practices and rites. A tiefling offspring is almost always female, with a chance to have multiple arms. They also need more meat then other Tieflings and are more likely to have sharper teeth

Those with this bloodline are able to cast Mage armour and Amour of Agathys. They have an increase in Strength  

Oni

Oni are usually classified as lower class fiends that do not associate with a higher fiend, thus not sharing the higher fiends powers with their decedents. it is believed that Oni are the true state of fiend and the first to come to this plane.
Known for their straight horns and big fangs, have a tendency to look more like their fiend counterparts. at one point they were the most common of the bloodlines, but fear and fighting has left them in a more neutral state of uncommon.

More likely to know firebolt and other fire spells. They have an increase in strength.  

Natural/Wild magic

These are an interesting breed of Tieflings. They are not created from a pact with a fiend, but instead with excess amounts of natural magic invading the body during conception. Mostly found in areas of high fey energy, some call this a Fey Tiefling. They tend to have a more human look to them, though some have odd features like one goat leg, uneven horns, or such. since a Tiefling of fiend origins can birth a Tiefling of Magic origins, some see it as a way to cleanse the blood.

Those with this bloodline ae able to cast the spell Thaumaturgy and hellish rebuke. The hellish rebuke is different in that once you hit high enough level, the elemental damage becomes random each time it activates. They have an increase in intelligence