Ignan Soul

Though all fire genasi claim ancestry to efreet, or other sapient beings of the Plane of Fire, for some the bloodline runs closer to the surface. For those sorcerers with an Ignan Soul, their powers are drawn directly from the primordial fires that warm the cosmos. Though unaspected, and free from the moral whims of other bloodlines, those born to the power of fire invariably burn bright and fierce, and display a familiarity with fire few but an elemental denizen could claim

Flame Speaker

The arcane magic you command is infused with elemental fire. At level one, you can speak, read, and write Primordial. Knowing this language allows you to understand and be understood by those who speak its dialects: Aquan, Auran, Ignan, and Terran. Furthermore, you gain the cantrip Control Flames. Control Flames does not count against the limit of cantrips set by your Sorcerer level. 

Igneous Blood

The adrenaline of combat runs molten through your veins. Starting at 1st level, you can use a bonus action on your turn to cause your skin to glow and emanate heat like a furnace.  You radiate light like a torch, and can maintain this state for as long as desired. However, when struck by a melee attack you can cause the heat to burst out in the attackers direction as a reaction, doing 1D4 plus your sorcerer level in damage. Afterwards the heat dissipates, and at the start of your next turn roll a 1D6. On a 3, 4, 5, or 6 you regain the ability. On a 1 or 2, you do not. On every following turn you can roll again until the ability is reacquired. Regardless, Igneous Blood resets at the end of combat. 

Heart of the Cinder

The fires of your spells ignite the heat within your soul. At 6th level, whenever you start casting a spell of 1st level or higher that deals fire damage, flames erupt from you. This eruption causes creatures of your choice that you can see within 10 feet of you to take fire damage (choose each time this ability activates) equal to half your sorcerer level plus your charisma modifier.

Ignited Speed

The heat of your soul powers your movement. Starting at 14th level, your movement increases by 20 feet per round, and once per long rest you can cast a 3rd level Haste on yourself, as a bonus action, and without having the spell prepared or using a spell slot, acquiring all of the spell's bonuses and weaknesses as the normal spell. In this state your form becomes indistinct in a heat haze, and you are also subject to the effects of the Blur spell for the remainder of the haste. 

Leap into the Fire

Your bond with the plane of fire is complete. Starting at 18th level you gain immunity to fire, and you can transverse the Plane of Fire. For a number of times per day equal to your charisma modifier,  you can leap into any fire large enough to accommodate your body (such as a firepit, or a furnace), and emerge from another fire of similar size that you have seen. This ability acts as the Teleport spell, with the same familiarity rules, save that any being that is also not immune to fire, and you attempt to bring with you, will take 10d6 + your sorcerer level in damage from their passage through the plane of fire. If you try to use this ability as an attack, the creature you are trying to leap with must make a spell save against your spell save DC. This save is charisma based.